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<!-- span class="title">SeisComP Release</span -->
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<span class="version">6.9.0</span>
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<section id="glossary">
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<span id="id1"></span><h1>Glossary<a class="headerlink" href="#glossary" title="Permalink to this heading">¶</a></h1>
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<p>The glossary is partly extracted from New Manual of Observatory Practice and some information
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is taken from Modern Global Seismology.</p>
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<section id="scname-terms">
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<h2><cite>SeisComP</cite> terms<a class="headerlink" href="#scname-terms" title="Permalink to this heading">¶</a></h2>
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<dl class="glossary">
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<dt id="term-binding">binding<a class="headerlink" href="#term-binding" title="Permalink to this term">¶</a></dt><dd><p>A binding is a set of configuration options to configure the connection between a
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<a class="reference internal" href="#term-module"><span class="xref std std-term">module</span></a> and a station. Bindings are located in <code class="docutils literal notranslate"><span class="pre">etc/key/modulename/station_NET_STA</span></code>.
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They are either written to the database or used to create native configuration files
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for standalone modules. The concepts section on <a class="reference internal" href="concepts/configuration.html#concepts-configuration"><span class="std std-ref">configuration</span></a>
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provides more details.</p>
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</dd>
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<dt id="term-module">module<a class="headerlink" href="#term-module" title="Permalink to this term">¶</a></dt><dd><p>A module is usually a binary executable that does a certain job such as <a class="reference internal" href="../apps/seedlink.html#seedlink"><span class="std std-ref">seedlink</span></a>
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or <a class="reference internal" href="../apps/scautopick.html#scautopick"><span class="std std-ref">scautopick</span></a>. The concepts section on <a class="reference internal" href="concepts/modules.html#concepts-modules"><span class="std std-ref">modules</span></a>
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provides more details.</p>
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</dd>
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<dt id="term-plugin">plugin<a class="headerlink" href="#term-plugin" title="Permalink to this term">¶</a></dt><dd><p>An extension to a module. The concepts section on <a class="reference internal" href="concepts/plugins.html#concepts-plugins"><span class="std std-ref">plugins</span></a>
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provides more details.</p>
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</dd>
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<dt id="term-profile">profile<a class="headerlink" href="#term-profile" title="Permalink to this term">¶</a></dt><dd><p>A profile is a special <a class="reference internal" href="#term-binding"><span class="xref std std-term">binding</span></a>. Instead of defining the same set of configuration
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options again and again for many stations a profile can be used. Instead of configuring a
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stations like:</p>
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<div class="highlight-sh notranslate"><div class="highlight"><pre><span></span>seedlink
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scautopick
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</pre></div>
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</div>
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<p>which refers to <code class="docutils literal notranslate"><span class="pre">etc/key/seedlink/station_NET_STA</span></code> and <code class="docutils literal notranslate"><span class="pre">etc/key/scautopick/station_NET_STA</span></code>
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a profile can be given:</p>
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<div class="highlight-sh notranslate"><div class="highlight"><pre><span></span>seedlink:geofon
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scautopick:teleseismic
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</pre></div>
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</div>
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<p>which refers to <code class="file docutils literal notranslate"><span class="pre">etc/key/seedlink/profile_geofon</span></code> and
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<code class="file docutils literal notranslate"><span class="pre">etc/key/scautopick/profile_teleseismic</span></code>.
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Changing the profile changes the bindings of all stations that use this profile.</p>
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</dd>
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<dt id="term-RecordStream">RecordStream<a class="headerlink" href="#term-RecordStream" title="Permalink to this term">¶</a></dt><dd><p>Interface to access data records from data processing modules.
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<a class="reference internal" href="#term-SeisComP"><span class="xref std std-term">SeisComP</span></a> applications access waveform data through the
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<a class="reference internal" href="concepts/recordstream.html#concepts-recordstream"><span class="std std-ref">RecordStream interface</span></a>.</p>
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</dd>
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<dt id="term-standalone-module">standalone module<a class="headerlink" href="#term-standalone-module" title="Permalink to this term">¶</a></dt><dd><p>A module that needs to convert the configuration or do not use the default
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configuration options (see below) is called a standalone modules.
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Examples for standalone modules are <a class="reference internal" href="../apps/seedlink.html#seedlink"><span class="std std-ref">seedlink</span></a>, <a class="reference internal" href="../apps/slarchive.html#slarchive"><span class="std std-ref">slarchive</span></a> or <a class="reference internal" href="../apps/slmon.html#slmon"><span class="std std-ref">slmon</span></a>.</p>
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</dd>
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<dt id="term-trunk">trunk<a class="headerlink" href="#term-trunk" title="Permalink to this term">¶</a></dt><dd><p>The module and library collection which forms and uses the SeisComP
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framework. The Application class is part of this framework. All trunk
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modules share a common configuration schema and a database with
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Inventory, EventParameters, Configuration, Routing and QC schemas.
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Representatives are <a class="reference internal" href="../apps/scautoloc.html#scautoloc"><span class="std std-ref">scautoloc</span></a> and <a class="reference internal" href="../apps/scautopick.html#scautopick"><span class="std std-ref">scautopick</span></a> and the GUI
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collection with <a class="reference internal" href="../apps/scolv.html#scolv"><span class="std std-ref">scolv</span></a>, <a class="reference internal" href="../apps/scmv.html#scmv"><span class="std std-ref">scmv</span></a>, <a class="reference internal" href="../apps/scrttv.html#scrttv"><span class="std std-ref">scrttv</span></a> and <a class="reference internal" href="../apps/scesv.html#scesv"><span class="std std-ref">scesv</span></a>.</p>
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</dd>
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||
</dl>
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||
</section>
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<hr class="docutils" />
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<section id="scientific-and-technical-terms">
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<h2>Scientific and technical terms<a class="headerlink" href="#scientific-and-technical-terms" title="Permalink to this heading">¶</a></h2>
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<dl class="glossary">
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<dt id="term-AIC">AIC<a class="headerlink" href="#term-AIC" title="Permalink to this term">¶</a></dt><dd><p>Aikaike Information Criterion used for refinement of phase picks.
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Phase pickers for picking P and S phase arrivals based on AIC may reach
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high accuracy if tuned well.</p>
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</dd>
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<dt id="term-aftershocks">aftershocks<a class="headerlink" href="#term-aftershocks" title="Permalink to this term">¶</a></dt><dd><p>Earthquakes that follow a large earthquake in a sequence. They are smaller than the mainshock
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and within 1-2 fault lengths distance from the mainshock fault. Aftershocks can continue over
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a period of weeks, months, or years, decreasing in frequency with time. In general, the larger
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the mainshock, the larger and more numerous the aftershocks, and the longer they will continue.</p>
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</dd>
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<dt id="term-amplitude">amplitude<a class="headerlink" href="#term-amplitude" title="Permalink to this term">¶</a></dt><dd><ol class="arabic simple">
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<li><p>General term used for an observation of a wave at a particular time.</p></li>
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<li><p>QuakeML object. Amplitudes are computed, e.g. for computing
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<a class="reference internal" href="#term-magnitude"><span class="xref std std-term">magnitudes</span></a> of different types. Another type is the
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<a class="reference internal" href="#term-SNR"><span class="xref std std-term">SNR</span></a>. Amplitude computation depends on the type.</p></li>
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</ol>
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<p>In <cite>SeisComP</cite> amplitudes are computed automatically by <a class="reference internal" href="../apps/scautopick.html#scautopick"><span class="std std-ref">scautopick</span></a> and
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<a class="reference internal" href="../apps/scamp.html#scamp"><span class="std std-ref">scamp</span></a> or interactively by <a class="reference internal" href="../apps/scolv.html#scolv"><span class="std std-ref">scolv</span></a>.</p>
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</dd>
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<dt id="term-array">array<a class="headerlink" href="#term-array" title="Permalink to this term">¶</a></dt><dd><p>A set of observing sensors at which the observed and sought signal are mostly coherent.
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If the sensors are seismometers or barometers measuring infrasound, the terms
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<a class="reference internal" href="#term-seismic-array"><span class="xref std std-term">seismic array</span></a> or <a class="reference internal" href="#term-infrasound-array"><span class="xref std std-term">infrasound array</span></a> are used, respectively.
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Arrays are different from a <a class="reference internal" href="#term-network"><span class="xref std std-term">network</span></a> by the applied methods, e.g.
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||
<a class="reference internal" href="#term-F-K"><span class="xref std std-term">F-K</span></a> analysis, <a class="reference internal" href="#term-beam"><span class="xref std std-term">beam</span></a> forming or <a class="reference internal" href="#term-vespagram"><span class="xref std std-term">vespagram</span></a> analysis.</p>
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||
</dd>
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||
<dt id="term-ATF">ATF<a class="headerlink" href="#term-ATF" title="Permalink to this term">¶</a></dt><dd><p>The <a class="reference internal" href="#term-array-transfer-function"><span class="xref std std-term">array transfer function</span></a> or <a class="reference internal" href="#term-array-response-function"><span class="xref std std-term">array response function</span></a>
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||
describes the sensitivity and resolution of an <a class="reference internal" href="#term-array"><span class="xref std std-term">array</span></a> to signals
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||
propagating through the array with a particular <a class="reference internal" href="#term-azimuth"><span class="xref std std-term">azimuth</span></a>, <a class="reference internal" href="#term-slowness"><span class="xref std std-term">slowness</span></a>
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and <a class="reference internal" href="#term-frequency"><span class="xref std std-term">frequency</span></a>.</p>
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||
</dd>
|
||
<dt id="term-array-response-function">array response function<a class="headerlink" href="#term-array-response-function" title="Permalink to this term">¶</a></dt><dd><p>A synonym of <a class="reference internal" href="#term-ATF"><span class="xref std std-term">ATF</span></a> or <a class="reference internal" href="#term-array-transfer-function"><span class="xref std std-term">array transfer function</span></a>.</p>
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||
</dd>
|
||
<dt id="term-array-transfer-function">array transfer function<a class="headerlink" href="#term-array-transfer-function" title="Permalink to this term">¶</a></dt><dd><p>A synonym of <a class="reference internal" href="#term-ATF"><span class="xref std std-term">ATF</span></a> or <a class="reference internal" href="#term-array-response-function"><span class="xref std std-term">array response function</span></a>.</p>
|
||
</dd>
|
||
<dt id="term-ArcLink">ArcLink<a class="headerlink" href="#term-ArcLink" title="Permalink to this term">¶</a></dt><dd><p>ArcLink complements <a class="reference internal" href="#term-SeedLink"><span class="xref std std-term">SeedLink</span></a> by providing access to archived waveform
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||
data. Arclink was distributed with <a class="reference internal" href="#term-SeisComP"><span class="xref std std-term">SeisComP</span></a> until version 3.0.</p>
|
||
</dd>
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||
<dt id="term-arrival">arrival<a class="headerlink" href="#term-arrival" title="Permalink to this term">¶</a></dt><dd><ol class="arabic simple">
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||
<li><p>The appearance of seismic energy on a seismic record</p></li>
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<li><p>QuakeML object. The detected phase onset associated to an origin in <cite>SeisComP</cite>.</p></li>
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</ol>
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</dd>
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||
<dt id="term-arrival-time">arrival time<a class="headerlink" href="#term-arrival-time" title="Permalink to this term">¶</a></dt><dd><p>The time at which a particular phase of a seismic wave arrives at a station.</p>
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</dd>
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<dt id="term-asthenosphere">asthenosphere<a class="headerlink" href="#term-asthenosphere" title="Permalink to this term">¶</a></dt><dd><p>The ductile part of the Earth, just below the brittle <a class="reference internal" href="#term-lithosphere"><span class="xref std std-term">lithosphere</span></a>,
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||
in the upper mantle. The lithosphere/asthenosphere reaches down to about 200 km.</p>
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||
</dd>
|
||
<dt id="term-azimuth">azimuth<a class="headerlink" href="#term-azimuth" title="Permalink to this term">¶</a></dt><dd><p>In general a direction measured clock-wise in degrees against north. In seismology used to
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||
measure the direction from a seismic source to a seismic station recording this event.</p>
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||
</dd>
|
||
<dt id="term-beam">beam<a class="headerlink" href="#term-beam" title="Permalink to this term">¶</a></dt><dd><p>The sum of signals observed at an <a class="reference internal" href="#term-array"><span class="xref std std-term">array</span></a> shifted with respect
|
||
to the array reference coordinate assuming a particular <a class="reference internal" href="#term-slowness"><span class="xref std std-term">slowness</span></a>
|
||
and <a class="reference internal" href="#term-azimuth"><span class="xref std std-term">azimuth</span></a>. Optimum values for slowness and azimuth can be
|
||
found, e.g. by <a class="reference internal" href="#term-F-K"><span class="xref std std-term">F-K</span></a> analysis.</p>
|
||
</dd>
|
||
<dt id="term-beam-packing">beam packing<a class="headerlink" href="#term-beam-packing" title="Permalink to this term">¶</a></dt><dd><p>Equivalent to the <a class="reference internal" href="#term-F-K"><span class="xref std std-term">F-K</span></a> analysis where the <a class="reference internal" href="#term-beam"><span class="xref std std-term">beam</span></a> and the related
|
||
parameters such as <a class="reference internal" href="#term-beam-power"><span class="xref std std-term">beam power</span></a> or <a class="reference internal" href="#term-semblance"><span class="xref std std-term">semblance</span></a> are formed in the
|
||
time domain. Seismograms from the <a class="reference internal" href="#term-array"><span class="xref std std-term">array</span></a> stations are shifted according
|
||
to the considered ranges of <a class="reference internal" href="#term-slowness"><span class="xref std std-term">slowness</span></a> and <a class="reference internal" href="#term-backazimuth"><span class="xref std std-term">backazimuth</span></a> or
|
||
<a class="reference internal" href="#term-wave-number"><span class="xref std std-term">wave number</span></a> and summed to form the beam.</p>
|
||
</dd>
|
||
<dt id="term-beam-power">beam power<a class="headerlink" href="#term-beam-power" title="Permalink to this term">¶</a></dt><dd><p>The energy of <a class="reference internal" href="#term-beam"><span class="xref std std-term">beam</span></a> within a defined time window.</p>
|
||
</dd>
|
||
<dt id="term-backazimuth">backazimuth<a class="headerlink" href="#term-backazimuth" title="Permalink to this term">¶</a></dt><dd><p>The direction from the seismic station towards a seismic source, measured in degrees clock-wise
|
||
against north; sometimes also just called azimuth.</p>
|
||
</dd>
|
||
<dt id="term-Benioff-zone">Benioff zone<a class="headerlink" href="#term-Benioff-zone" title="Permalink to this term">¶</a></dt><dd><p>see <a class="reference internal" href="#term-Wadati-Benioff-zone"><span class="xref std std-term">Wadati-Benioff zone</span></a></p>
|
||
</dd>
|
||
<dt id="term-body-wave">body wave<a class="headerlink" href="#term-body-wave" title="Permalink to this term">¶</a></dt><dd><p>A seismic wave that propagates through the interior of the Earth, as opposed to
|
||
surface waves that propagate near the Earth’s surface. <a class="reference internal" href="#term-P-wave"><span class="xref std std-term">P</span></a> and <a class="reference internal" href="#term-S-wave"><span class="xref std std-term">S waves</span></a>, which shake
|
||
the ground in different ways, are examples.</p>
|
||
</dd>
|
||
<dt id="term-body-wave-magnitude">body wave magnitude<a class="headerlink" href="#term-body-wave-magnitude" title="Permalink to this term">¶</a></dt><dd><p>see <a class="reference internal" href="#term-magnitude-body-wave-mb"><span class="xref std std-term">magnitude, body-wave (mb)</span></a></p>
|
||
</dd>
|
||
<dt id="term-calibration">calibration<a class="headerlink" href="#term-calibration" title="Permalink to this term">¶</a></dt><dd><p>The process of determining the response function (distortion of the input signal) and
|
||
sensitivity of an instrument or its derived component.</p>
|
||
</dd>
|
||
<dt id="term-CAV">CAV<a class="headerlink" href="#term-CAV" title="Permalink to this term">¶</a></dt><dd><p>cumulated absolute velocity</p>
|
||
</dd>
|
||
<dt id="term-CI">CI<a class="headerlink" href="#term-CI" title="Permalink to this term">¶</a></dt><dd><p>Characteristic Intensity</p>
|
||
</dd>
|
||
<dt id="term-channel-code">channel code<a class="headerlink" href="#term-channel-code" title="Permalink to this term">¶</a></dt><dd><p>Description of characteristics of data related to the recording sensor and
|
||
data logger as well as instrument responses, sampling frequencies, etc.
|
||
The standard codes are defined in the <span id="id2"><em>SEED Reference Manual</em> [<a class="reference internal" href="references.html#id252" title="SEED Reference Manual. USGS, 2012. URL: http://www.fdsn.org/pdf/SEEDManual_V2.4.pdf.">31</a>]</span>.</p>
|
||
</dd>
|
||
<dt id="term-Circum-Pacific-belt">Circum-Pacific belt<a class="headerlink" href="#term-Circum-Pacific-belt" title="Permalink to this term">¶</a></dt><dd><p>The zone surrounding the Pacific Ocean that is characterized by frequent and strong
|
||
earthquakes and many volcanoes as well as high tsunami hazard. Also called the Ring of Fire.</p>
|
||
</dd>
|
||
<dt id="term-coda">coda<a class="headerlink" href="#term-coda" title="Permalink to this term">¶</a></dt><dd><p>The tail of a seismic signal, usually with exponentially decaying amplitudes, which
|
||
follow a strong wave arrival. Coda waves are due to scattering and superposition of multi-path arrivals.</p>
|
||
</dd>
|
||
<dt id="term-coda-phase">coda phase<a class="headerlink" href="#term-coda-phase" title="Permalink to this term">¶</a></dt><dd><p>A detection of a single phase of unknown path found within the coda signal envelope,
|
||
designated as tx, e.g. Px or Sx.</p>
|
||
</dd>
|
||
<dt id="term-coherent">coherent<a class="headerlink" href="#term-coherent" title="Permalink to this term">¶</a></dt><dd><p>Seismic signals detected on various seismic sensors of a seismic array or network are said to
|
||
be coherent if they are related to each other in time, amplitude and/or waveform because they
|
||
come from the same seismic source.</p>
|
||
</dd>
|
||
<dt id="term-color">color<a class="headerlink" href="#term-color" title="Permalink to this term">¶</a></dt><dd><p>Colors are given in hexadecimal representation or by <a class="reference internal" href="#term-color-keyword-name"><span class="xref std std-term">color keyword names</span></a>.</p>
|
||
</dd>
|
||
<dt id="term-color-keyword-name">color keyword name<a class="headerlink" href="#term-color-keyword-name" title="Permalink to this term">¶</a></dt><dd><p>Color keyword names allow the specification of color values by names
|
||
representing color codes instead of RGB or hexadecimal representation. Find examples
|
||
on the <a class="reference external" href="https://www.w3.org/TR/SVG11/types.html#ColorKeywords">website of W3C</a>.
|
||
Color keyword names have been introduced in SeisComP in version 4.4.0.</p>
|
||
</dd>
|
||
<dt id="term-convolution">convolution<a class="headerlink" href="#term-convolution" title="Permalink to this term">¶</a></dt><dd><p>A mathematically equivalent operation that describes the action of a linear (mechanical
|
||
and/or electronic) system on a signal, such as that of a filter on a seismic signal.</p>
|
||
</dd>
|
||
<dt id="term-core">core<a class="headerlink" href="#term-core" title="Permalink to this term">¶</a></dt><dd><p>The innermost part of the Earth. The outer core extends from about 2900 to about 5120 km below
|
||
the Earth’s surface and consists in its main components of a mixture of liquid iron and nickel.
|
||
The inner core is the central sphere of the Earth with a diameter of 1250 km and consists of solid metal.</p>
|
||
</dd>
|
||
<dt id="term-Core-Mantle-Boundary-CMB">Core-Mantle Boundary(CMB)<a class="headerlink" href="#term-Core-Mantle-Boundary-CMB" title="Permalink to this term">¶</a></dt><dd><p>see <a class="reference internal" href="#term-Gutenberg-discontinuity"><span class="xref std std-term">Gutenberg discontinuity</span></a></p>
|
||
</dd>
|
||
<dt id="term-corner-frequency">corner frequency<a class="headerlink" href="#term-corner-frequency" title="Permalink to this term">¶</a></dt><dd><p>The frequency at which the curve representing the Fourier amplitude spectrum of a recorded seismic
|
||
signal abruptly changes its slope. For earthquakes, this frequency is a property of the source and
|
||
related to fault size, rupture velocity, source duration and stress drop in the source. Also the
|
||
frequency at which the transfer function / magnification curve of a recording system changes its slope.</p>
|
||
</dd>
|
||
<dt id="term-creep">creep<a class="headerlink" href="#term-creep" title="Permalink to this term">¶</a></dt><dd><p>Slow, more or less continuous movement occurring on faults due to ongoing tectonic deformation.
|
||
Also applied to slow movement of landslide masses down a slope because of gravitational forces.
|
||
Faults that are creeping do not tend to have large earthquakes. This fault condition is commonly
|
||
referred to as unlocked.</p>
|
||
</dd>
|
||
<dt id="term-crust">crust<a class="headerlink" href="#term-crust" title="Permalink to this term">¶</a></dt><dd><p>The outermost major layer of the Earth, ranging from about 10 to 70 km in thickness worldwide.
|
||
The oceanic crust is thinner (about 10 to 15 km) than the continental crust (about 25 to 70 km).
|
||
The uppermost 15-35 km of the crust is brittle enough to produce earthquakes. The seismogenic crust
|
||
is separated from the lower crust by the brittle-ductile boundary. The crust is usually characterized
|
||
by P-wave velocities below 8 km/s (average velocity of about 6 km/s).</p>
|
||
</dd>
|
||
<dt id="term-delay">delay<a class="headerlink" href="#term-delay" title="Permalink to this term">¶</a></dt><dd><p>The time difference between the arrival time and the end time of the last record achieved plus
|
||
the half record length. The delay can be computed by <a class="reference internal" href="../apps/scqc.html#scqc"><span class="std std-ref">scqc</span></a>.</p>
|
||
</dd>
|
||
<dt id="term-depth-Phase">depth Phase<a class="headerlink" href="#term-depth-Phase" title="Permalink to this term">¶</a></dt><dd><p>see <a class="reference internal" href="#term-pP-phase"><span class="xref std std-term">pP phase</span></a> or <a class="reference internal" href="#term-sP-phase"><span class="xref std std-term">sP phase</span></a></p>
|
||
</dd>
|
||
<dt id="term-detection">detection<a class="headerlink" href="#term-detection" title="Permalink to this term">¶</a></dt><dd><p>Identification of an arrival of a seismic signal with amplitudes above and/or signal shape
|
||
(waveform) different from seismic noise.</p>
|
||
</dd>
|
||
<dt id="term-directivity">directivity<a class="headerlink" href="#term-directivity" title="Permalink to this term">¶</a></dt><dd><p>An effect of a propagating fault rupture whereby the amplitudes of the generated ground motions
|
||
depend on the direction of wave propagation with respect to fault orientation and slip
|
||
direction (radiation pattern). The directivity and thus the radiation pattern is different for
|
||
<a class="reference internal" href="#term-P-wave"><span class="xref std std-term">P</span></a> and <a class="reference internal" href="#term-S-wave"><span class="xref std std-term">S waves</span></a>.</p>
|
||
</dd>
|
||
<dt id="term-EDA">EDA<a class="headerlink" href="#term-EDA" title="Permalink to this term">¶</a></dt><dd><p>Effective Design Acceleration</p>
|
||
</dd>
|
||
<dt id="term-EIDA">EIDA<a class="headerlink" href="#term-EIDA" title="Permalink to this term">¶</a></dt><dd><p>European Integrated Data Archive: <a class="reference external" href="http://www.orfeus-eu.org/data/eida/">http://www.orfeus-eu.org/data/eida/</a></p>
|
||
</dd>
|
||
<dt id="term-epicenter">epicenter<a class="headerlink" href="#term-epicenter" title="Permalink to this term">¶</a></dt><dd><p>Vertical projection of the hypocenter to the surface.</p>
|
||
</dd>
|
||
<dt id="term-event">event<a class="headerlink" href="#term-event" title="Permalink to this term">¶</a></dt><dd><ol class="arabic simple">
|
||
<li><p>General term used for a localized disturbance (earthquake, explosion, etc.) which generates seismic waves.</p></li>
|
||
<li><p>QuakeML object. The event is the parent object of several <a class="reference internal" href="#term-origin"><span class="xref std std-term">origins</span></a>.
|
||
Among these origins a preferred origin
|
||
and its <a class="reference internal" href="#term-preferred-magnitude"><span class="xref std std-term">preferred magnitude</span></a> is selected to represent the event.
|
||
An event can be seen as an earthquake folder
|
||
which contains information about earthquake parameters.</p></li>
|
||
</ol>
|
||
</dd>
|
||
<dt id="term-fault-plane-solution">fault-plane solution<a class="headerlink" href="#term-fault-plane-solution" title="Permalink to this term">¶</a></dt><dd><p>Representation of the fault activated in an earthquake and the caused direction of slip on the fault by
|
||
a circle with two intersecting curves looking like a beach ball. A fault-plane solution is found by the
|
||
analysis of seismic records at many stations of an earthquake to obtain the radiation pattern. From the
|
||
radiation pattern the fault parameter and the slip direction are determined using a stereographic
|
||
projection or its mathematical equivalent. The most common analysis uses the direction of first motion
|
||
of P wave onsets and yields two possible orientations for the fault rupture and the direction of seismic
|
||
slip. Another technique is to use the polarization of teleseismic <a class="reference internal" href="#term-S-wave"><span class="xref std std-term">S waves</span></a> and/or to measure amplitude
|
||
ratios between different phase types. Further inferences can be made from these data concerning the
|
||
principal axes of stress in the region of the earthquake. The principal stress axes determined by this
|
||
method are the compressional axis (also called the P-axis, i.e. the axis of greatest compression, or s1),
|
||
the tensional axis (also known as the T-axis, i.e., the axis of least compression, or s3), and the
|
||
intermediate axis (s2).</p>
|
||
</dd>
|
||
<dt id="term-filter-ing">filter(ing)<a class="headerlink" href="#term-filter-ing" title="Permalink to this term">¶</a></dt><dd><p>A filter attenuates certain frequencies of a (seismic) signal and amplifies others. The process of
|
||
filtering can be accomplished electronically while recording or numerically in a computer. Filtering also
|
||
occurs naturally as seismic energy passes through the Earth.</p>
|
||
<p>The available and integrated filters in <cite>SeisComP</cite> are documented in <a class="reference internal" href="filter-grammar.html#filter-grammar"><span class="std std-ref">Filter Grammar</span></a>.</p>
|
||
</dd>
|
||
<dt id="term-first-motion">first motion<a class="headerlink" href="#term-first-motion" title="Permalink to this term">¶</a></dt><dd><p>The first noticeable displacement in a seismogram caused by the arrival of a P wave at the seismometer.
|
||
Upward motion of the ground at the seismometer indicates a dilatation at the source, downward motion
|
||
indicates a compression. Due to the presence of seismic noise the proper polarity of the first motion
|
||
may be difficult to recognize.</p>
|
||
</dd>
|
||
<dt id="term-F-K">F-K<a class="headerlink" href="#term-F-K" title="Permalink to this term">¶</a></dt><dd><p>F-K refers to a 2-D <a class="reference internal" href="#term-Fourier-analysis"><span class="xref std std-term">Fourier analysis</span></a> where the base functions
|
||
are defined, e.g. by ranges of <a class="reference internal" href="#term-frequency"><span class="xref std std-term">frequency</span></a> and <a class="reference internal" href="#term-wave-number"><span class="xref std std-term">wave number</span></a>.
|
||
F-K analysis is applied for signal detection by transforming time series
|
||
recorded at several sensors, e.g. seismic or infrasound <a class="reference internal" href="#term-array"><span class="xref std std-term">array</span></a>
|
||
stations to the time and space domain.</p>
|
||
<p>The equivalent to F-K analysis in the time domain is <a class="reference internal" href="#term-beam-packing"><span class="xref std std-term">beam packing</span></a>.</p>
|
||
</dd>
|
||
<dt id="term-focal-mechanism">focal mechanism<a class="headerlink" href="#term-focal-mechanism" title="Permalink to this term">¶</a></dt><dd><p>see <a class="reference internal" href="#term-fault-plane-solution"><span class="xref std std-term">fault-plane solution</span></a></p>
|
||
</dd>
|
||
<dt id="term-foreshocks">foreshocks<a class="headerlink" href="#term-foreshocks" title="Permalink to this term">¶</a></dt><dd><p>Earthquakes that occur in a series of earthquakes before the largest earthquake, termed the mainshock.
|
||
Foreshocks may precede the mainshock by seconds to weeks and usually originate at or near the focus
|
||
of the larger earthquake. Not all mainshocks have foreshocks.</p>
|
||
</dd>
|
||
<dt id="term-Fourier-spectrum">Fourier spectrum<a class="headerlink" href="#term-Fourier-spectrum" title="Permalink to this term">¶</a></dt><dd><p>The relative amplitudes (and phase angles) at different frequencies that are derived from a time series
|
||
by Fourier analysis.</p>
|
||
</dd>
|
||
<dt id="term-Fourier-analysis">Fourier analysis<a class="headerlink" href="#term-Fourier-analysis" title="Permalink to this term">¶</a></dt><dd><p>The mathematical operation that resolves a time series (for example, a recording of ground motion)
|
||
into a series of numbers that characterize the relative amplitude and phase components of the signal
|
||
as a function of frequency.</p>
|
||
</dd>
|
||
<dt id="term-frequency">frequency<a class="headerlink" href="#term-frequency" title="Permalink to this term">¶</a></dt><dd><p>Number of cycles of a repeating signal per unit time, typically per second.</p>
|
||
</dd>
|
||
<dt id="term-frequency-domain">frequency domain<a class="headerlink" href="#term-frequency-domain" title="Permalink to this term">¶</a></dt><dd><p>The transformation of a seismic signal from the time domain (as a seismogram) to the frequency
|
||
domain is conducted by a <a class="reference internal" href="#term-Fourier-analysis"><span class="xref std std-term">Fourier analysis</span></a>. The signal is represented in the frequency domain by
|
||
the amplitude and phase components as a function of frequency (see spectrum). The representations of
|
||
a seismic signal in the time and in the frequency domain are equivalent in a mathematical sense.
|
||
For some procedures of data analysis the time-domain representation of a seismic record is more
|
||
suitable while for others the frequency-domain approach is more appropriate and efficient.</p>
|
||
</dd>
|
||
<dt id="term-gempa-GmbH">gempa GmbH<a class="headerlink" href="#term-gempa-GmbH" title="Permalink to this term">¶</a></dt><dd><p><a class="reference external" href="http://www.gempa.de/">gempa GmbH</a> is a spin-off from <a class="reference internal" href="#term-GFZ"><span class="xref std std-term">GFZ</span></a>
|
||
offering a range of services and products to monitor, process and analyze
|
||
seismicity. It is the main development and service company for <cite>SeisComP</cite>.</p>
|
||
</dd>
|
||
<dt id="term-GEOFON">GEOFON<a class="headerlink" href="#term-GEOFON" title="Permalink to this term">¶</a></dt><dd><p>GEOFON (<a class="reference external" href="https://geofon.gfz-potsdam.de">https://geofon.gfz-potsdam.de</a>) is part of the Modular Earth Science
|
||
Infrastructure (MESI) at <a class="reference internal" href="#term-GFZ"><span class="xref std std-term">GFZ</span></a>.</p>
|
||
</dd>
|
||
<dt id="term-geometrical-spreading">geometrical spreading<a class="headerlink" href="#term-geometrical-spreading" title="Permalink to this term">¶</a></dt><dd><p>The component of reduction in wave amplitude due to the radial spreading of seismic energy with
|
||
increasing distance from a given source.</p>
|
||
</dd>
|
||
<dt id="term-GFZ">GFZ<a class="headerlink" href="#term-GFZ" title="Permalink to this term">¶</a></dt><dd><p>Helmholtz Centre Potsdam <a class="reference external" href="http://www.gfz-potsdam.de/">German Research Centre for Geosciences</a>.
|
||
<cite>SeisComP</cite> was originally developed at GFZ.</p>
|
||
</dd>
|
||
<dt id="term-GMPE">GMPE<a class="headerlink" href="#term-GMPE" title="Permalink to this term">¶</a></dt><dd><p>Ground Motion Prediction Equation</p>
|
||
</dd>
|
||
<dt id="term-Green-s-function">Green’s function<a class="headerlink" href="#term-Green-s-function" title="Permalink to this term">¶</a></dt><dd><p>A mathematical representation that, in reference to earthquake shaking, is used to represent the
|
||
ground motion caused by instantaneous slip on a small part of a fault. Green’s functions can be
|
||
summed over a large fault surface to compute the ground shaking for a large earthquake rupturing
|
||
a fault of finite size. The fractional fault-slip events that are summed can be records from
|
||
small earthquakes on the fault or they can be theoretically computed small-earthquake records.</p>
|
||
</dd>
|
||
<dt id="term-Gutenberg-discontinuity">Gutenberg discontinuity<a class="headerlink" href="#term-Gutenberg-discontinuity" title="Permalink to this term">¶</a></dt><dd><p>The seismic velocity discontinuity marking the core-mantle boundary (CMB) at which the velocity
|
||
of P waves drops from about 13.7 km/s to about 8.0 km/s and the velocity of <a class="reference internal" href="#term-S-wave"><span class="xref std std-term">S waves</span></a> drops from
|
||
about 7.3 km/s to 0 km/s. The CMB reflects the change from the solid mantle material to the
|
||
fluid outer core.</p>
|
||
</dd>
|
||
<dt id="term-GUI">GUI<a class="headerlink" href="#term-GUI" title="Permalink to this term">¶</a></dt><dd><p>Graphical use interface, e.g. <a class="reference internal" href="../apps/scolv.html#scolv"><span class="std std-ref">scolv</span></a>.</p>
|
||
</dd>
|
||
<dt id="term-hypocenter">hypocenter<a class="headerlink" href="#term-hypocenter" title="Permalink to this term">¶</a></dt><dd><p>Coordinates of an earthquake point source. Hypocenters based on <a class="reference internal" href="#term-P-wave"><span class="xref std std-term">P</span></a> and <a class="reference internal" href="#term-S-wave"><span class="xref std std-term">S wave</span></a>
|
||
first arrivals point to the place where the rupture process starts. For large earthquakes the
|
||
source location determined by <a class="reference internal" href="#term-P-wave"><span class="xref std std-term">P wave</span></a> first arrivals can differ significantly from the location of
|
||
maximum energy release.</p>
|
||
</dd>
|
||
<dt id="term-Ia">Ia<a class="headerlink" href="#term-Ia" title="Permalink to this term">¶</a></dt><dd><p>Arias Intensity</p>
|
||
</dd>
|
||
<dt id="term-infrasound-array">infrasound array<a class="headerlink" href="#term-infrasound-array" title="Permalink to this term">¶</a></dt><dd><p>An <a class="reference internal" href="#term-array"><span class="xref std std-term">array</span></a> of barometers measuring infrasound signals.</p>
|
||
</dd>
|
||
<dt id="term-intensity">intensity<a class="headerlink" href="#term-intensity" title="Permalink to this term">¶</a></dt><dd><p>A measure of the effects of an earthquake at a particular place at the Earth’s surface on humans
|
||
and (or) structures. The intensity at a point depends not only upon the strength of the earthquake
|
||
(magnitude) but also upon the distance from the earthquake, the depth of the hypocenter and the
|
||
local geology at that point. Several scales exist, most of them giving the intensity in 12 degrees,
|
||
usually written as Roman numerals. Most frequently used are at present the European Macroseismic
|
||
Scale (EMS-98), and in the United States the Modified Mercalli scale and the Rossi-Forel scale.
|
||
There are many different intensity values for one earthquake, depending on how far you are away
|
||
from the epicenter; this is unlike the magnitude value, which is one number for each earthquake
|
||
as a measure of the amount of seismic wave energy released by it.</p>
|
||
</dd>
|
||
<dt id="term-interplate-intraplate">interplate/intraplate<a class="headerlink" href="#term-interplate-intraplate" title="Permalink to this term">¶</a></dt><dd><p>Intraplate pertains to processes within the Earth’s crustal plates. Interplate pertains to
|
||
processes between the plates.</p>
|
||
</dd>
|
||
<dt id="term-interplate-coupling">interplate coupling<a class="headerlink" href="#term-interplate-coupling" title="Permalink to this term">¶</a></dt><dd><p>The qualitative ability of a subduction thrust fault to lock and accumulate stress. Strong
|
||
interplate coupling implies that the fault is locked and capable of accumulation stress whereas
|
||
weak coupling implies that the fault is unlocked or only capable of accumulating low stress.
|
||
A fault with weak interplate coupling could be aseismic or could slip by creep.</p>
|
||
</dd>
|
||
<dt id="term-inventory">inventory<a class="headerlink" href="#term-inventory" title="Permalink to this term">¶</a></dt><dd><p>The inventory is the collection of all available meta data related to <a class="reference internal" href="#term-network"><span class="xref std std-term">network</span></a>,
|
||
<a class="reference internal" href="#term-station"><span class="xref std std-term">station</span></a>, <a class="reference internal" href="#term-location-code"><span class="xref std std-term">location code</span></a>, station <a class="reference internal" href="#term-channel-code"><span class="xref std std-term">channel code</span></a>,
|
||
characteristics of sensors and data loggers, etc. More details are given in
|
||
the concepts section <a class="reference internal" href="concepts/inventory.html#concepts-inventory"><span class="std std-ref">Inventory</span></a>.</p>
|
||
</dd>
|
||
<dt id="term-latency">latency<a class="headerlink" href="#term-latency" title="Permalink to this term">¶</a></dt><dd><p>Time difference between the end times of consecutive records.
|
||
The latency can be computed by <a class="reference internal" href="../apps/scqc.html#scqc"><span class="std std-ref">scqc</span></a>.</p>
|
||
</dd>
|
||
<dt id="term-lithosphere">lithosphere<a class="headerlink" href="#term-lithosphere" title="Permalink to this term">¶</a></dt><dd><p>The outer solid part of the Earth, including crust and uppermost mantle. The lithosphere is
|
||
about 100 km thick, although its thickness is age-dependent (older lithosphere is thicker).
|
||
At some locations the lithosphere below the crust is brittle enough to produce earthquakes by
|
||
faulting, such as within a subducted oceanic plate.</p>
|
||
</dd>
|
||
<dt id="term-location-code">location code<a class="headerlink" href="#term-location-code" title="Permalink to this term">¶</a></dt><dd><p>Description of particular sensor location associated to a station. The standard
|
||
location codes are defined in the <span id="id3"><em>SEED Reference Manual</em> [<a class="reference internal" href="references.html#id252" title="SEED Reference Manual. USGS, 2012. URL: http://www.fdsn.org/pdf/SEEDManual_V2.4.pdf.">31</a>]</span>.</p>
|
||
</dd>
|
||
<dt id="term-Love-wave">Love wave<a class="headerlink" href="#term-Love-wave" title="Permalink to this term">¶</a></dt><dd><p>A major type of surface waves having a horizontal motion that is transverse (or perpendicular)
|
||
to the direction of propagation. It is named after A. E. H. Love, the English mathematician
|
||
who discovered it.</p>
|
||
</dd>
|
||
<dt id="term-leaky-mode">leaky mode<a class="headerlink" href="#term-leaky-mode" title="Permalink to this term">¶</a></dt><dd><p>A seismic surface wave which is imperfectly trapped, e.g., within a low-velocity layer or a
|
||
sequence of layers, so that its energy leaks or escapes across a layer boundary causing some
|
||
attenuation.</p>
|
||
</dd>
|
||
<dt id="term-low-velocity-layer-zone">low-velocity layer/zone<a class="headerlink" href="#term-low-velocity-layer-zone" title="Permalink to this term">¶</a></dt><dd><p>Any layer in the Earth in which seismic wave velocities are lower than in the layers above and below.</p>
|
||
</dd>
|
||
<dt id="term-magnification-curve">magnification curve<a class="headerlink" href="#term-magnification-curve" title="Permalink to this term">¶</a></dt><dd><p>A diagram showing the dependence of amplification, e.g. of the seismic ground motion by a
|
||
seismograph, as a function of frequency.</p>
|
||
</dd>
|
||
<dt id="term-magnitude">magnitude<a class="headerlink" href="#term-magnitude" title="Permalink to this term">¶</a></dt><dd><p>A number that characterizes the relative size of an earthquake. The magnitude is based on
|
||
<a class="reference internal" href="#term-amplitude"><span class="xref std std-term">amplitude</span></a> measurement of the maximum motion recorded by a seismograph
|
||
(sometimes for waves of a particular frequency),
|
||
corrected for the attenuation with distance. Several scales have been defined, but the most commonly used are:</p>
|
||
<ol class="arabic simple">
|
||
<li><p>local magnitude (ML), commonly referred to as “Richter magnitude”</p></li>
|
||
<li><p>surface-wave magnitude (Ms)</p></li>
|
||
<li><p>body-wave magnitude (mb)</p></li>
|
||
<li><p>moment magnitude (Mw).</p></li>
|
||
</ol>
|
||
<p>The magnitude scales 1-3 have limited range and applicability and do not
|
||
satisfactorily measure the
|
||
size of the largest earthquakes. The moment magnitude (Mw) scale, based on
|
||
the concept of seismic moment,
|
||
is uniformly applicable to all earthquake sizes but is more difficult to
|
||
compute than the other types. In
|
||
principal, all magnitude scales could be cross calibrated to yield the same
|
||
value for any given earthquake, but
|
||
this expectation has proven to be only approximately true, thus the
|
||
magnitude type as well as its value is needed to be specified.</p>
|
||
<p>Additional or modified magnitudes can be computed by providing plugins.</p>
|
||
<p>In <cite>SeisComP</cite> magnitudes are computed automatically by <a class="reference internal" href="../apps/scmag.html#scmag"><span class="std std-ref">scmag</span></a> or interactively
|
||
by <a class="reference internal" href="../apps/scolv.html#scolv"><span class="std std-ref">scolv</span></a>.</p>
|
||
</dd>
|
||
<dt id="term-magnitude-local-ML">magnitude, local (ML)<a class="headerlink" href="#term-magnitude-local-ML" title="Permalink to this term">¶</a></dt><dd><p>Magnitude scale introduced by Richter in the early 1930s (<span id="id4">Richter [<a class="reference internal" href="references.html#id62" title="C.F. Richter. An instrumental earthquake magnitude scale. Bull. Seismol. Soc. Am., 1:1 - 32, 1935. URL: https://resolver.caltech.edu/CaltechAUTHORS:20140804-143558638, doi:10.1785/BSSA0250010001.">57</a>]</span>)
|
||
to have a common scale for the strength of earthquakes. The basic observation
|
||
is the systematic decay of the logarithm of the maximum
|
||
amplitudes with increasing distance for different earthquakes described by:</p>
|
||
<div class="math">
|
||
<p><img src="../_images/math/b0ebe6e979dee4886949b4cda7beda6170c120d0.png" alt="ML = \log A_{max} - \log A_0"/></p>
|
||
</div><p>with A<sub>0</sub> as amplitude of a reference event. For the reference event
|
||
ML = 0 the formula can be rewritten to</p>
|
||
<div class="math">
|
||
<p><img src="../_images/math/c2480e17e843eda90dd925a3cfb2923484409583.png" alt="ML = \log A_{max} - 2.48 + 2.76 \log \Delta"/></p>
|
||
</div><p>with Δ being the distance of the station to the earthquake location. ML is a
|
||
magnitude scale for
|
||
recordings of earthquakes smaller than ML 7 at regional stations. It is
|
||
usually a measure of the
|
||
regional-distance S-wave on horizontal component records.
|
||
The original formula is only valid for records from a <a class="reference internal" href="#term-Wood-Anderson-seismometer"><span class="xref std std-term">Wood-Anderson torsion
|
||
seismometer</span></a> with a natural period of
|
||
0.8 s and shallow earthquakes in California. Therefore calibration functions
|
||
for other regions and wider depth ranges are necessary.
|
||
A <a class="reference internal" href="#term-Wood-Anderson-seismometer"><span class="xref std std-term">Wood-Anderson torsion seismometer</span></a> is
|
||
simulated when measuring amplitudes.</p>
|
||
<p>For amplitudes measured on the vertical component records, additional
|
||
correction factors have to be applied. ML saturates at
|
||
magnitudes around 7 because the maximum amplitudes of larger earthquakes
|
||
occur at longer periods than
|
||
the bandpass of 0.1 s and 3 s for the magnitude calculation.</p>
|
||
<p>In <cite>SeisComP</cite> a modified local magnitude
|
||
<a class="reference internal" href="#term-magnitude-local-vertical-MLv"><span class="xref std std-term">MLv</span></a> is determined by simulation
|
||
of a Wood-Anderson instrument and then measuring the amplitude in a 150 s
|
||
time window on the vertical component of station with distances smaller than 8°.</p>
|
||
<ul class="simple">
|
||
<li><p>Amplitude unit in <cite>SeisComP</cite>: <strong>millimeter</strong> (mm)</p></li>
|
||
</ul>
|
||
<p>Read the <a class="reference internal" href="../apps/global_ml.html#global-ml"><span class="std std-ref">technical documentation</span></a> for more details and
|
||
the configuration.</p>
|
||
</dd>
|
||
<dt id="term-magnitude-local-custom-MLc">magnitude, local custom (MLc)<a class="headerlink" href="#term-magnitude-local-custom-MLc" title="Permalink to this term">¶</a></dt><dd><p>The local magnitude measured on the horizontal components with
|
||
custom parametric or non-parametric function, configurable amplitude
|
||
filtering, <a class="reference internal" href="#term-Wood-Anderson-seismometer"><span class="xref std std-term">Wood-Anderson torsion seismometer</span></a> and distance measures.</p>
|
||
<ul class="simple">
|
||
<li><p>Amplitude unit in <cite>SeisComP</cite>: <strong>millimeter</strong> (mm)</p></li>
|
||
</ul>
|
||
<p>Read the <a class="reference internal" href="../apps/global_mlc.html#global-mlc"><span class="std std-ref">technical documentation</span></a> for more details and
|
||
the configuration.</p>
|
||
</dd>
|
||
<dt id="term-magnitude-local-horizontal-MLh">magnitude, local horizontal (MLh)<a class="headerlink" href="#term-magnitude-local-horizontal-MLh" title="Permalink to this term">¶</a></dt><dd><p>The local magnitude computed from amplitudes measured on the horizontal
|
||
components with a modified parametric calibration function as compared to
|
||
<a class="reference internal" href="#term-magnitude-local-ML"><span class="xref std std-term">ML</span></a>.</p>
|
||
<ul class="simple">
|
||
<li><p>Amplitude unit in <cite>SeisComP</cite>: <strong>millimeter</strong> (mm)</p></li>
|
||
</ul>
|
||
<p>Read the <a class="reference internal" href="../apps/global_mlh.html#global-mlh"><span class="std std-ref">technical documentation</span></a> for more details and
|
||
the configuration.</p>
|
||
</dd>
|
||
<dt id="term-magnitude-local-GNS-GEONET-MLr">magnitude, local GNS/GEONET (MLr)<a class="headerlink" href="#term-magnitude-local-GNS-GEONET-MLr" title="Permalink to this term">¶</a></dt><dd><p>Local magnitude calculated from <a class="reference internal" href="#term-magnitude-local-vertical-MLv"><span class="xref std std-term">MLv</span></a>
|
||
amplitudes based on GNS/GEONET specifications for New Zealand.</p>
|
||
<p>Read the <a class="reference internal" href="../apps/global_mlr.html#global-mlr"><span class="std std-ref">technical documentation</span></a> for more details and the configuration.</p>
|
||
</dd>
|
||
<dt id="term-magnitude-local-vertical-MLv">magnitude, local vertical (MLv)<a class="headerlink" href="#term-magnitude-local-vertical-MLv" title="Permalink to this term">¶</a></dt><dd><p>The <a class="reference internal" href="#term-magnitude-local-ML"><span class="xref std std-term">ML</span></a> magnitude with amplitudes measured on
|
||
the vertical component instead of the horizontals.</p>
|
||
<ul class="simple">
|
||
<li><p>Amplitude unit in <cite>SeisComP</cite>: <strong>millimeter</strong> (mm)</p></li>
|
||
</ul>
|
||
<p>Read the <a class="reference internal" href="../apps/global_mlv.html#global-mlv"><span class="std std-ref">technical documentation</span></a> for more details and the configuration.</p>
|
||
</dd>
|
||
<dt id="term-magnitude-Nuttli-MN">magnitude, Nuttli (MN)<a class="headerlink" href="#term-magnitude-Nuttli-MN" title="Permalink to this term">¶</a></dt><dd><p>Nuttli magnitude for Canada and other Cratonic regions.</p>
|
||
<ul class="simple">
|
||
<li><p>Amplitude unit in <cite>SeisComP</cite>: <strong>meter/second</strong> (m/s)</p></li>
|
||
</ul>
|
||
<p>Read the <a class="reference internal" href="../apps/global_mn.html#global-mn"><span class="std std-ref">technical documentation</span></a> for more details and the configuration.</p>
|
||
</dd>
|
||
<dt id="term-magnitude-body-wave-mb">magnitude, body-wave (mb)<a class="headerlink" href="#term-magnitude-body-wave-mb" title="Permalink to this term">¶</a></dt><dd><p>Magnitude developed for teleseismic body waves. mb is defined on the amplitude
|
||
of the first few cycles of the P-wave restituted to <a class="reference internal" href="#term-WWSSN_SP"><span class="xref std std-term">WWSSN_SP</span></a>.</p>
|
||
<ul class="simple">
|
||
<li><p>Amplitude unit in <cite>SeisComP</cite>: <strong>nanometer</strong> (nm)</p></li>
|
||
</ul>
|
||
<p>Read the <a class="reference internal" href="../apps/global_mb.html#global-mb"><span class="std std-ref">technical documentation</span></a> for more details and the configuration.</p>
|
||
</dd>
|
||
<dt id="term-magnitude-broadband-body-wave-mB_BB">magnitude, broadband body-wave (mB_BB)<a class="headerlink" href="#term-magnitude-broadband-body-wave-mB_BB" title="Permalink to this term">¶</a></dt><dd><p>mB_BB is the term recommended by the IASPEI commission for
|
||
<a class="reference internal" href="#term-magnitude-broadband-body-wave-mB"><span class="xref std std-term">magnitude, broadband body-wave (mB)</span></a> which is used in <cite>SeisComP</cite>.</p>
|
||
</dd>
|
||
<dt id="term-magnitude-broadband-body-wave-mB">magnitude, broadband body-wave (mB)<a class="headerlink" href="#term-magnitude-broadband-body-wave-mB" title="Permalink to this term">¶</a></dt><dd><p>mB is a magnitude based on body waves like <a class="reference internal" href="#term-magnitude-body-wave-mb"><span class="xref std std-term">mb</span></a>,
|
||
but with the amplitude measured in a broad frequency range and longer time windows.
|
||
mB is used as a synonym for <a class="reference internal" href="#term-magnitude-broadband-body-wave-mB_BB"><span class="xref std std-term">mB_BB</span></a>.</p>
|
||
<ul class="simple">
|
||
<li><p>Amplitude unit in <cite>SeisComP</cite> is <strong>nanometer per second</strong> (nm/s)</p></li>
|
||
</ul>
|
||
<p>Read the <a class="reference internal" href="../apps/global_mb_bb.html#global-mb-bb"><span class="std std-ref">technical documentation</span></a> for more details and the configuration.</p>
|
||
</dd>
|
||
<dt id="term-magnitude-cumulative-body-wave-mBc">magnitude, cumulative body-wave (mBc)<a class="headerlink" href="#term-magnitude-cumulative-body-wave-mBc" title="Permalink to this term">¶</a></dt><dd><p>mBc is the cumulative body-wave magnitude. See <span id="id5">Bormann and Wylegalla [<a class="reference internal" href="references.html#id17" title="P. Bormann and K. Wylegalla. Quick estimator of the size of great earthquakes. EOS, 86(46):464, 2005.">40</a>]</span>
|
||
and <span id="id6">Bormann and Saul [<a class="reference internal" href="references.html#id19" title="P. Bormann and J. Saul. A Fast, Non-saturating Magnitude Estimator for Great Earthquakes. Seismol. Res. Lett., 80(5):808 - 816, 2009. doi:10.1785/gssrl.80.5.808.">39</a>]</span> for details.</p>
|
||
</dd>
|
||
<dt id="term-magnitude-surface-wave-Ms">magnitude, surface wave (Ms)<a class="headerlink" href="#term-magnitude-surface-wave-Ms" title="Permalink to this term">¶</a></dt><dd><p>Ms is a magnitude scale based on teleseismic surface waves. Historically, Ms
|
||
is based on measurements of
|
||
the maximum horizontal true ground motion displacement amplitudes</p>
|
||
<div class="math">
|
||
<p><img src="../_images/math/712686e0db840ef121e384b1bf28f7552b5a45a9.png" alt="A_{Hmax} =\sqrt{{A_N}^2 + {A_E}^2}"/></p>
|
||
</div><p>in the total seismogram at periods around 20 s. For shallow earthquakes the dominant
|
||
long-period signals are the surface waves. The period of 20 s corresponds to the Airy
|
||
phase, a local minimum in the group velocity dispersion curve of Rayleigh surface waves.
|
||
For measuring amplitudes a correction for the WWSSN_LP instrument response is applied.</p>
|
||
<p>The Moscow-Prague equation for surface wave magnitude is given by</p>
|
||
<div class="math">
|
||
<p><img src="../_images/math/93c80b427369a5485ba5001e33597d9ad656e040.png" alt="M_s = \log \left(\frac{A_{Hmax}}{T}\right) + 1.66 \log(\Delta) + 3.3"/></p>
|
||
</div><p>where T is the measured period.</p>
|
||
<div class="math">
|
||
<p><img src="../_images/math/e5eedbf96d0b9836511e050896a63b594690134f.png" alt="M_s = \log \left(\frac{A}{T}\right)max + 1.66 \log(\Delta) + 3.3"/></p>
|
||
</div><p>Here, the maximum ground particle velocity, (A/T)max, is used instead of the AHmax to
|
||
allow a broader spectrum of dominant periods. This formula is valid for distances of
|
||
2° to 160° and source depths smaller than 50 km.</p>
|
||
<ul class="simple">
|
||
<li><p>Amplitude unit in <cite>SeisComP</cite> is <strong>meter per second</strong> (m/s)</p></li>
|
||
</ul>
|
||
</dd>
|
||
<dt id="term-magnitude-surface-wave-Ms_20">magnitude, surface wave (Ms_20)<a class="headerlink" href="#term-magnitude-surface-wave-Ms_20" title="Permalink to this term">¶</a></dt><dd><p>Ms_20 is the <a class="reference internal" href="#term-magnitude-surface-wave-Ms"><span class="xref std std-term">Ms</span></a> surface-wave magnitude
|
||
at <em>T=20</em> s period based on the recommendations
|
||
by the IASPEI magnitude working group issued on 27 March, 2013.</p>
|
||
<ul class="simple">
|
||
<li><p>Amplitude unit in <cite>SeisComP</cite>: nanometer (nm)</p></li>
|
||
</ul>
|
||
<p>Read the <a class="reference internal" href="../apps/global_ms_20.html#global-ms-20"><span class="std std-ref">technical documentation</span></a> for more details and the configuration.</p>
|
||
</dd>
|
||
<dt id="term-magnitude-broadband-surface-wave-Ms-BB">magnitude, broadband surface wave (Ms(BB))<a class="headerlink" href="#term-magnitude-broadband-surface-wave-Ms-BB" title="Permalink to this term">¶</a></dt><dd><p>Ms(BB) is a broadband magnitude scale based on teleseismic surface waves.
|
||
In contrast to <a class="reference internal" href="#term-magnitude-surface-wave-Ms"><span class="xref std std-term">Ms</span></a>, amplitudes for Ms(BB)
|
||
are measured as the maximum on vertical true ground motion velocity seismograms without
|
||
instrument simulation or restitution.</p>
|
||
<p>The Moscow-Prague equation for surface wave magnitude is applied as given by</p>
|
||
<div class="math">
|
||
<p><img src="../_images/math/e265a2c12ff5dda233e41927cae4ead315596b47.png" alt="M_s = \log \left(\frac{A}{2\pi}\right) + 1.66 \log(\Delta) + 3.3"/></p>
|
||
</div><ul class="simple">
|
||
<li><p>Amplitude unit in <cite>SeisComP</cite>: <strong>meter per second</strong> (m/s)</p></li>
|
||
<li><p>Period range: all</p></li>
|
||
<li><p>Distance range: 2 - 160°</p></li>
|
||
<li><p>Depth range: 0 - 100 km</p></li>
|
||
<li><p>Time window: distance (km) / 3.5 km/s + 30 s</p></li>
|
||
</ul>
|
||
</dd>
|
||
<dt id="term-magnitude-duration-Md">magnitude, duration (Md)<a class="headerlink" href="#term-magnitude-duration-Md" title="Permalink to this term">¶</a></dt><dd><p>The duration magnitude measured on the coda wave train.</p>
|
||
<p>Read the <a class="reference internal" href="../apps/global_md.html#global-md"><span class="std std-ref">technical documentation</span></a> for more details and the configuration.</p>
|
||
</dd>
|
||
<dt id="term-magnitude-JMA-M_JMA">magnitude, JMA (M_JMA)<a class="headerlink" href="#term-magnitude-JMA-M_JMA" title="Permalink to this term">¶</a></dt><dd><p>M(JMA) is a magnitude similar to the Ms, but the formula is calibrated for instruments
|
||
with 5 s period at local distances. The data set for the calibration was gained by the
|
||
Japan Meteorological Agency (JMA).</p>
|
||
<div class="math">
|
||
<p><img src="../_images/math/f73ef943923c3e1057e14204950603563902e3bf.png" alt="M(JMA) = \log \sqrt{{A_N}^2 + {A_E}^2} + 1.73 \log\Delta - 0.83"/></p>
|
||
</div><p>This equation is valid for local (< 2000 km) and shallow (< 80 km)
|
||
earthquakes. For deeper earthquakes additional correction functions have
|
||
to be applied (<span id="id7">Katsumata [<a class="reference internal" href="references.html#id44" title="A. Katsumata. Comparison of Magnitudes Estimated by the Japan Meteorological Agency with Moment Magnitudes for Intermediate and Deep Earthquakes. Bull. Seism. Soc., 86(3):832 - 842, 1996.">49</a>]</span>).</p>
|
||
<ul class="simple">
|
||
<li><p>Amplitude unit in <cite>SeisComP</cite>: <strong>micrometer</strong> (um)</p></li>
|
||
<li><p>Time window: 150 s</p></li>
|
||
<li><p>Epicentral distance range: 0 - 20°</p></li>
|
||
<li><p>Depth range: 0 - 80 km</p></li>
|
||
</ul>
|
||
</dd>
|
||
<dt id="term-magnitude-moment-Mw">magnitude, moment (Mw)<a class="headerlink" href="#term-magnitude-moment-Mw" title="Permalink to this term">¶</a></dt><dd><p>The moment magnitude is a magnitude scale related to the seismic moment M<sub>0</sub> and
|
||
thus to the released seismic energy.
|
||
To obtain Mw the seismic moment is first determined, e.g. by a moment tensor inversion.
|
||
Then the Mw is gained by the following standard relationship between seismic moment
|
||
and the moment magnitude (M<sub>0</sub> in cgs units of dyn*cm):</p>
|
||
<div class="math">
|
||
<p><img src="../_images/math/b094f771f607c37cea7e1cfb617585a207516afa.png" alt="Mw = \frac{2}{3}(\log M_0 - 16.1)"/></p>
|
||
</div><p>This equation is analog to the relation between M<sub>s</sub> and M<sub>0</sub>.</p>
|
||
</dd>
|
||
<dt id="term-magnitude-averaged-moment-Mw-avg">magnitude, averaged moment (Mw(avg))<a class="headerlink" href="#term-magnitude-averaged-moment-Mw-avg" title="Permalink to this term">¶</a></dt><dd><p>Moment magnitude derived as a weighted average of other magnitudes.</p>
|
||
</dd>
|
||
<dt id="term-magnitude-broadband-P-wave-moment-Mwp">magnitude, broadband P-wave moment (Mwp)<a class="headerlink" href="#term-magnitude-broadband-P-wave-moment-Mwp" title="Permalink to this term">¶</a></dt><dd><p>The Mwp is a rapid estimate of the moment magnitude based on the
|
||
first-arrival P waves on broadband seismograph records. The displacement
|
||
seismograms of the P wave portion are considered as source time function
|
||
approximation. The seismic moment is estimated for each station by
|
||
integrating the displacement records. The combination of multiple records
|
||
results in an estimation of the moment magnitude without correction
|
||
for the source mechanism (<span id="id8">Tsuboi <em>et al.</em> [<a class="reference internal" href="references.html#id79" title="S. Tsuboi, K. Abe, K. Takano, and Y. Yamanaka. Rapid determination of Mw from broadband P waveforms. Bull. Seismol. Soc. Am., 1995. doi:10.1785/BSSA0850020606.">63</a>]</span>).</p>
|
||
<ul class="simple">
|
||
<li><p>Amplitude unit in <cite>SeisComP</cite>: <strong>nanometer times second</strong> (nm*s)</p></li>
|
||
<li><p>Time window: 95 s</p></li>
|
||
<li><p>Epicentral distance range: 5 - 105°</p></li>
|
||
</ul>
|
||
</dd>
|
||
<dt id="term-magnitude-derived-mB-Mw-mB">magnitude, derived mB (Mw(mB))<a class="headerlink" href="#term-magnitude-derived-mB-Mw-mB" title="Permalink to this term">¶</a></dt><dd><p>Moment magnitude derived from <a class="reference internal" href="#term-magnitude-broadband-body-wave-mB"><span class="xref std std-term">mB</span></a>
|
||
magnitudes using linear conversion:</p>
|
||
<p>Mw(mB) = 1.30 mB - 2.18</p>
|
||
</dd>
|
||
<dt id="term-magnitude-derived-Mwp-Mw-Mwp">magnitude, derived Mwp (Mw(Mwp))<a class="headerlink" href="#term-magnitude-derived-Mwp-Mw-Mwp" title="Permalink to this term">¶</a></dt><dd><p>Moment magnitude derived from <a class="reference internal" href="#term-magnitude-broadband-P-wave-moment-Mwp"><span class="xref std std-term">Mwp</span></a>
|
||
magnitudes using linear conversion after <span id="id9">Whitmore <em>et al.</em> [<a class="reference internal" href="references.html#id85" title="P.M. Whitmore, S. Tsuboi, B. Hirshorn, and T.J. Sokolowski. Magnitude dependent correction for Mwp. Science of Tsunami Hazards, 20(4):, 2002.">65</a>]</span>:</p>
|
||
<p>Mw(Mwp) = 1.31 Mwp - 1.91</p>
|
||
</dd>
|
||
<dt id="term-magnitude-summary-M">magnitude, summary (M)<a class="headerlink" href="#term-magnitude-summary-M" title="Permalink to this term">¶</a></dt><dd><p>Summary magnitude derived from multiple other magnitudes by <a class="reference internal" href="../apps/scmag.html#scmag"><span class="std std-ref">scmag</span></a>.</p>
|
||
</dd>
|
||
<dt id="term-mainshock">mainshock<a class="headerlink" href="#term-mainshock" title="Permalink to this term">¶</a></dt><dd><p>The largest earthquake in a sequence, sometimes preceded by one or more foreshocks,
|
||
and almost always followed by many aftershocks.</p>
|
||
</dd>
|
||
<dt id="term-mantle">mantle<a class="headerlink" href="#term-mantle" title="Permalink to this term">¶</a></dt><dd><p>The part of the Earth’s interior between the core and the crust.</p>
|
||
</dd>
|
||
<dt id="term-microearthquake">microearthquake<a class="headerlink" href="#term-microearthquake" title="Permalink to this term">¶</a></dt><dd><p>An earthquake that is not perceptible by man and can be recorded by seismographs only.
|
||
Typically, a microearthquake has a magnitude of 2 or less on the Richter scale.</p>
|
||
</dd>
|
||
<dt id="term-microseism">microseism<a class="headerlink" href="#term-microseism" title="Permalink to this term">¶</a></dt><dd><ol class="arabic simple">
|
||
<li><p>In a broader sense: A more or less continuous motion in the Earth in a wide frequency
|
||
range that is unrelated to any earthquake and caused by a variety of usually uncorrelated
|
||
(incoherent) natural and artificial (man-made) sources.</p></li>
|
||
<li><p>In a more specific sense: That part of seismic noise that is generated by wave motions
|
||
on lakes and oceans and their interaction with shores, typically with periods between
|
||
about 2 to 9 s (the stronger secondary microseisms), and 11 to 18 s (the weaker
|
||
primary microseisms).</p></li>
|
||
</ol>
|
||
</dd>
|
||
<dt id="term-miniSeed">miniSeed<a class="headerlink" href="#term-miniSeed" title="Permalink to this term">¶</a></dt><dd><p>miniSEED is the
|
||
standard for the exchange of seismic time series. It uses a fixed record
|
||
length and applies data compression as defined in <span id="id10"><em>SEED Reference Manual</em> [<a class="reference internal" href="references.html#id252" title="SEED Reference Manual. USGS, 2012. URL: http://www.fdsn.org/pdf/SEEDManual_V2.4.pdf.">31</a>]</span>.</p>
|
||
</dd>
|
||
<dt id="term-MMI">MMI<a class="headerlink" href="#term-MMI" title="Permalink to this term">¶</a></dt><dd><p>Modified Mercalli Intensity</p>
|
||
</dd>
|
||
<dt id="term-Moho">Moho<a class="headerlink" href="#term-Moho" title="Permalink to this term">¶</a></dt><dd><p>The abbreviation for the <a class="reference internal" href="#term-Mohorovicic-discontinuity"><span class="xref std std-term">Mohorovičić discontinuity</span></a>.</p>
|
||
</dd>
|
||
<dt id="term-Mohorovicic-discontinuity">Mohorovičić discontinuity<a class="headerlink" href="#term-Mohorovicic-discontinuity" title="Permalink to this term">¶</a></dt><dd><p>The discontinuity in seismic velocities that defines the boundary between crust and mantle
|
||
of the Earth. Named after the Croatian seismologist Andrija Mohorovičič (1857-1936) who
|
||
discovered it. The boundary is between 20 and 60 km deep beneath the continents and between
|
||
5 and 10 km deep beneath the ocean floor.</p>
|
||
</dd>
|
||
<dt id="term-moment-tensor">moment tensor<a class="headerlink" href="#term-moment-tensor" title="Permalink to this term">¶</a></dt><dd><p>Moment tensors or seismic moment tensors describe the equivalent forces
|
||
due to seismic point sources, e.g. earthquakes with rupture dimensions
|
||
much smaller than the distance at which they are observed.</p>
|
||
</dd>
|
||
<dt id="term-network">network<a class="headerlink" href="#term-network" title="Permalink to this term">¶</a></dt><dd><p>A set of stations typically maintained by one or more institutions and
|
||
tuned to record particular signals.</p>
|
||
</dd>
|
||
<dt id="term-network-magnitude">network magnitude<a class="headerlink" href="#term-network-magnitude" title="Permalink to this term">¶</a></dt><dd><ol class="loweralpha simple">
|
||
<li><p>The network magnitude is a magnitude value summarizing several <a class="reference internal" href="#term-station-magnitude"><span class="xref std std-term">station magnitude</span></a> values
|
||
of one <a class="reference internal" href="#term-origin"><span class="xref std std-term">origin</span></a>. Read the documentation of <a class="reference internal" href="../apps/scmag.html#scmag"><span class="std std-ref">scmag</span></a> for the details.</p></li>
|
||
<li><p>QuakeML object.</p></li>
|
||
</ol>
|
||
</dd>
|
||
<dt id="term-noise-seismic">noise (seismic)<a class="headerlink" href="#term-noise-seismic" title="Permalink to this term">¶</a></dt><dd><p>Incoherent natural or artificial perturbations caused by a diversity of agents and
|
||
distributed sources. One usually differentiates between ambient background noise and
|
||
instrumental noise. The former is due to natural (ocean waves, wind, rushing waters,
|
||
animal migration, ice movement, etc.) and/or man-made sources (traffic, machinery, etc.),
|
||
whereas instrumental (internal) noise may be due to the flicker noise of electronic
|
||
components and/or even Brownian molecular motions in mechanical components. Digital
|
||
data acquisition systems may add digitization noise due to their finite discrete
|
||
resolution (least significant digit). Very sensitive seismic recordings may contain
|
||
all these different noise components, however, usually their resolution is tuned so
|
||
that only seismic signals and to a certain degree also the ambient noise are resolved.
|
||
Disturbing noise can be reduced by selecting recording sites remote from noise sources,
|
||
installation of seismic sensors underground (e.g., in boreholes, tunnels or abandoned
|
||
mines) or by suitable filter procedures (improvement of the signal-to-noise ratio).</p>
|
||
</dd>
|
||
<dt id="term-Nyquist-frequency">Nyquist frequency<a class="headerlink" href="#term-Nyquist-frequency" title="Permalink to this term">¶</a></dt><dd><p>Half of the digital sampling rate. It is the minimum number of counts per second
|
||
needed to define unambiguously a particular frequency. If the seismic signal contains
|
||
energy in a frequency range above the Nyquist frequency the signal distortions are
|
||
called aliasing.</p>
|
||
</dd>
|
||
<dt id="term-onset">onset<a class="headerlink" href="#term-onset" title="Permalink to this term">¶</a></dt><dd><p>The first appearance of a seismic signal on a record.</p>
|
||
</dd>
|
||
<dt id="term-origin">origin<a class="headerlink" href="#term-origin" title="Permalink to this term">¶</a></dt><dd><ol class="arabic simple">
|
||
<li><p>Location (hypocenter), Time and strength estimation of an earthquake based on seismic
|
||
phases and amplitudes</p></li>
|
||
<li><p>QuakeML object</p></li>
|
||
</ol>
|
||
</dd>
|
||
<dt id="term-origin-time">origin time<a class="headerlink" href="#term-origin-time" title="Permalink to this term">¶</a></dt><dd><p>Estimated source time of an event belonging to a certain origin; describes the
|
||
rupture start time. Attribute of the QuakeML object Origin, see <a class="reference internal" href="#term-origin"><span class="xref std std-term">origin</span></a>.</p>
|
||
</dd>
|
||
<dt id="term-phase">phase<a class="headerlink" href="#term-phase" title="Permalink to this term">¶</a></dt><dd><ol class="arabic simple">
|
||
<li><p>A stage in periodic motion, such as wave motion or the motion of an oscillator,
|
||
measured with respect to a given initial point and expressed in angular measure.</p></li>
|
||
<li><p>A pulse of seismic energy arriving at a definite time, which passed the Earth
|
||
on a specific path.</p></li>
|
||
<li><p>Attribute of the QuakeML object Arrival, see <a class="reference internal" href="#term-arrival"><span class="xref std std-term">arrival</span></a>.</p></li>
|
||
</ol>
|
||
</dd>
|
||
<dt id="term-P-phase">P phase<a class="headerlink" href="#term-P-phase" title="Permalink to this term">¶</a></dt><dd><p>The P phase is the arrival of the direct P wave that traveled through the Earth’s
|
||
crust and mantle observed in epicentral distances up to 100°.</p>
|
||
</dd>
|
||
<dt id="term-Pdiff-phase">Pdiff phase<a class="headerlink" href="#term-Pdiff-phase" title="Permalink to this term">¶</a></dt><dd><p>The long-period P-wave energy can be diffracted at the CMB forming at distances larger
|
||
than 100° the Pdiff phase. The reason for the diffraction is the large reduction of the
|
||
P wave velocity at the CMB from about 13.7 km/s to 8 km/s. The amplitude of Pdiff is
|
||
relatively small. Pdiff is observed at distances where the outer core forms the “core
|
||
shadow” (see also <a class="reference internal" href="#term-PKP-phase"><span class="xref std std-term">PKP phase</span></a>).</p>
|
||
</dd>
|
||
<dt id="term-Pg-phase">Pg phase<a class="headerlink" href="#term-Pg-phase" title="Permalink to this term">¶</a></dt><dd><p>Pg is the direct P wave arriving first in local distances less than 100 km. For larger
|
||
distances Pn arrives first (see <a class="reference internal" href="#term-Pn-phase"><span class="xref std std-term">Pn phase</span></a> for details).</p>
|
||
</dd>
|
||
<dt id="term-PGA">PGA<a class="headerlink" href="#term-PGA" title="Permalink to this term">¶</a></dt><dd><p>Peak Ground Acceleration</p>
|
||
</dd>
|
||
<dt id="term-PGD">PGD<a class="headerlink" href="#term-PGD" title="Permalink to this term">¶</a></dt><dd><p>Peak Ground Displacement</p>
|
||
</dd>
|
||
<dt id="term-PGV">PGV<a class="headerlink" href="#term-PGV" title="Permalink to this term">¶</a></dt><dd><p>Peak Ground Velocity</p>
|
||
</dd>
|
||
<dt id="term-Pn-phase">Pn phase<a class="headerlink" href="#term-Pn-phase" title="Permalink to this term">¶</a></dt><dd><p>Pn is the P head wave along the Moho arriving first at local distances larger than
|
||
100 km (depending on the crustal thickness). Pn has usually smaller amplitudes than Pg.</p>
|
||
</dd>
|
||
<dt id="term-PcP-phase">PcP phase<a class="headerlink" href="#term-PcP-phase" title="Permalink to this term">¶</a></dt><dd><p>The P wave that is reflected at the CMB forms the PcP. At epicentral distances between
|
||
30° and 55° PcP is often recorded as sharp pulse.</p>
|
||
</dd>
|
||
<dt id="term-PKiKP-phase">PKiKP phase<a class="headerlink" href="#term-PKiKP-phase" title="Permalink to this term">¶</a></dt><dd><p>A P wave that travels through the Earth’s crust and mantle and is reflected at the
|
||
outer core-inner core boundary. At distances between 100° and 113° PKiKP can be the
|
||
first arrival if no Pdiff is observed.</p>
|
||
</dd>
|
||
<dt id="term-PKP-phase">PKP phase<a class="headerlink" href="#term-PKP-phase" title="Permalink to this term">¶</a></dt><dd><p>The direct P waves traversing the Earth’s crust, mantle and outer core without
|
||
reflection is called PKP. The outer core is a fluid causing a strong refraction at
|
||
the CMB into the outer core. The strong refraction of the seismic rays into the
|
||
core causes a “core shadow” that commences at epicentral distances of around 100° and
|
||
stretches to around 140°. Only Pdiff can be observed in this distance range. PKP is
|
||
the first arrival at distances larger than around 143°. At a distance of 144° P waves
|
||
with several paths through the Earth’s core arrive at the same time (caustic) and
|
||
form a strong arrival.</p>
|
||
</dd>
|
||
<dt id="term-PP-phase">PP phase<a class="headerlink" href="#term-PP-phase" title="Permalink to this term">¶</a></dt><dd><p>PP is a reflected P wave at the Earth’s surface traversing the Earth’s crust and mantle.</p>
|
||
</dd>
|
||
<dt id="term-pP-phase">pP phase<a class="headerlink" href="#term-pP-phase" title="Permalink to this term">¶</a></dt><dd><p>A P wave that has a takeoff angle of greater than 90° at the source and therefore
|
||
is first reflected at the surface near the epicenter. The pP is a depth phase.
|
||
For shallow events and at teleseismic distances pP has nearly the same path as the P wave except
|
||
for the path from hypocenter of the earthquake to the reflection point at the surface.</p>
|
||
</dd>
|
||
<dt id="term-SEED">SEED<a class="headerlink" href="#term-SEED" title="Permalink to this term">¶</a></dt><dd><p>Standard for the Exchange of Earthquake Data, a data format for seismological
|
||
data and metadata (<a class="reference internal" href="#term-inventory"><span class="xref std std-term">inventory</span></a>).
|
||
It is controlled as a standard by the International Federation
|
||
of Digital Seismograph Networks (FDSN).
|
||
The current version is 2.4, updated August 2012.
|
||
Read <span id="id11"><em>SEED Reference Manual</em> [<a class="reference internal" href="references.html#id252" title="SEED Reference Manual. USGS, 2012. URL: http://www.fdsn.org/pdf/SEEDManual_V2.4.pdf.">31</a>]</span> for details.</p>
|
||
</dd>
|
||
<dt id="term-S-phase">S phase<a class="headerlink" href="#term-S-phase" title="Permalink to this term">¶</a></dt><dd><p>The S phase is the arrival of the direct <a class="reference internal" href="#term-S-wave"><span class="xref std std-term">S wave</span></a> that traveled through the Earth’s
|
||
crust and mantle observed in epicentral distances up to 100°.</p>
|
||
</dd>
|
||
<dt id="term-Sg-phase">Sg phase<a class="headerlink" href="#term-Sg-phase" title="Permalink to this term">¶</a></dt><dd><p>Sg is the direct <a class="reference internal" href="#term-S-wave"><span class="xref std std-term">S wave</span></a> arriving first in local distances less than 100 km. For larger
|
||
distances Sn arrives first (see <a class="reference internal" href="#term-Sn-phase"><span class="xref std std-term">Sn phase</span></a> for details).</p>
|
||
</dd>
|
||
<dt id="term-Sn-phase">Sn phase<a class="headerlink" href="#term-Sn-phase" title="Permalink to this term">¶</a></dt><dd><p>Sn is the S head wave along the Moho arriving first at local distances larger than
|
||
100 km (depending on the crustal thickness). Sn has usually smaller amplitudes than Sg.</p>
|
||
</dd>
|
||
<dt id="term-sP-phase">sP phase<a class="headerlink" href="#term-sP-phase" title="Permalink to this term">¶</a></dt><dd><p>A P wave starting as an <a class="reference internal" href="#term-S-phase"><span class="xref std std-term">S phase</span></a> at the source and arriving as P.
|
||
The S phase has a takeoff angle greater than 90° at the source and therefore
|
||
is first reflected at the surface near the epicenter and then converted into
|
||
a <a class="reference internal" href="#term-P-wave"><span class="xref std std-term">P wave</span></a> phase. The sP is therefore a depth phase. For shallow
|
||
events and at teleseismic distances sP has nearly the same path as the P
|
||
wave except for the path from hypocenter of the earthquake to the
|
||
reflection point at the surface.</p>
|
||
</dd>
|
||
<dt id="term-pick">pick<a class="headerlink" href="#term-pick" title="Permalink to this term">¶</a></dt><dd><ol class="arabic simple">
|
||
<li><p>Automatic or manual determined phase onset</p></li>
|
||
<li><p>QuakeML object</p></li>
|
||
</ol>
|
||
</dd>
|
||
<dt id="term-polarity">polarity<a class="headerlink" href="#term-polarity" title="Permalink to this term">¶</a></dt><dd><p>In seismology the direction of first motion on a seismogram, either up (positive, compression)
|
||
or down (negative, dilatation or relaxation).</p>
|
||
</dd>
|
||
<dt id="term-polarization">polarization<a class="headerlink" href="#term-polarization" title="Permalink to this term">¶</a></dt><dd><p>The shape and orientation in space of the ground-motion particle trajectory. It differs
|
||
for different types of seismic waves such as P, S and surface waves and may be ± linear
|
||
or elliptical, prograde or retrograde. It is also influenced by heterogeneities and
|
||
anisotropy of the medium in which the seismic waves propagate and depends on their
|
||
frequency or wavelength, respectively. The polarization of ground motion may be reconstructed
|
||
by analyzing three-component seismic recordings.</p>
|
||
</dd>
|
||
<dt id="term-preferred-magnitude">preferred magnitude<a class="headerlink" href="#term-preferred-magnitude" title="Permalink to this term">¶</a></dt><dd><ol class="arabic simple">
|
||
<li><p>The network magnitude representing the strength of an event best as
|
||
automatically selected by <a class="reference internal" href="../apps/scevent.html#scevent"><span class="std std-ref">scevent</span></a> or interactively.</p></li>
|
||
<li><p>Attribute of the QuakeML object Event, see <a class="reference internal" href="#term-event"><span class="xref std std-term">event</span></a>.</p></li>
|
||
</ol>
|
||
</dd>
|
||
<dt id="term-preferred-origin">preferred origin<a class="headerlink" href="#term-preferred-origin" title="Permalink to this term">¶</a></dt><dd><ol class="arabic simple">
|
||
<li><p>The origin representing the location of an event best; generally, the location based
|
||
on the most picks or reviewed/revised by an operator. The preferred origins
|
||
is automatically selected by <a class="reference internal" href="../apps/scevent.html#scevent"><span class="std std-ref">scevent</span></a> or interactively.</p></li>
|
||
<li><p>Attribute of the QuakeML object Event, see <a class="reference internal" href="#term-event"><span class="xref std std-term">event</span></a>.</p></li>
|
||
</ol>
|
||
</dd>
|
||
<dt id="term-QuakeML">QuakeML<a class="headerlink" href="#term-QuakeML" title="Permalink to this term">¶</a></dt><dd><p>A XML scheme developed as an open standard for seismological meta data
|
||
exchange (<a class="reference external" href="http://www.quakeml.org">http://www.quakeml.org</a>).</p>
|
||
</dd>
|
||
<dt id="term-radiation-pattern">radiation pattern<a class="headerlink" href="#term-radiation-pattern" title="Permalink to this term">¶</a></dt><dd><p>Dependence of the amplitudes of seismic <a class="reference internal" href="#term-P-wave"><span class="xref std std-term">P</span></a> and <a class="reference internal" href="#term-S-wave"><span class="xref std std-term">S waves</span></a> on the direction and take-off
|
||
angle under which their seismic rays have left the seismic source. It is controlled
|
||
by the type of source mechanism, e.g., the orientation of the earthquake fault plane
|
||
and slip direction in space.</p>
|
||
</dd>
|
||
<dt id="term-Rayleigh-wave">Rayleigh wave<a class="headerlink" href="#term-Rayleigh-wave" title="Permalink to this term">¶</a></dt><dd><p>A seismic surface wave causing a retrograde, elliptical motion of a particle at the free
|
||
surface, with no transverse motion. It is named after Lord Rayleigh (1842-1919), who
|
||
predicted its existence.</p>
|
||
</dd>
|
||
<dt id="term-ray-theory">ray theory<a class="headerlink" href="#term-ray-theory" title="Permalink to this term">¶</a></dt><dd><p>Theoretical approach, which treats wave propagation as the propagation of seismic rays.
|
||
It is an approximation, which yields good results for short wave length (high-frequency
|
||
approximation) and allows easy calculations of travel times.</p>
|
||
</dd>
|
||
<dt id="term-ray-tracing-method">ray-tracing method<a class="headerlink" href="#term-ray-tracing-method" title="Permalink to this term">¶</a></dt><dd><p>Computational method of calculating ground-shaking estimates that assumes that the
|
||
ground motion is composed of multiple arrivals of seismic rays and related energy
|
||
bundles (Gauss beams) that leave the source and are reflected or refracted at velocity
|
||
boundaries according to Snell’s Law. The amplitudes of reflected and refracted waves
|
||
at each boundary are recalculated according to the Law of Conservation of Energy.</p>
|
||
</dd>
|
||
<dt id="term-recurrence-interval">recurrence interval<a class="headerlink" href="#term-recurrence-interval" title="Permalink to this term">¶</a></dt><dd><p>The average time span between large earthquakes at a particular site. Also
|
||
termed ‘return period’.</p>
|
||
</dd>
|
||
<dt id="term-reflection">reflection<a class="headerlink" href="#term-reflection" title="Permalink to this term">¶</a></dt><dd><p>The energy or wave from a seismic source that has been returned (reflected) from an
|
||
interface between materials of different elastic properties within the Earth, just
|
||
as a mirror reflects light.</p>
|
||
</dd>
|
||
<dt id="term-refraction">refraction<a class="headerlink" href="#term-refraction" title="Permalink to this term">¶</a></dt><dd><p>The deflection, or bending, of the ray path of a seismic wave caused by its passage
|
||
from one material to another having different elastic properties.</p>
|
||
<p>Bending of a tsunami wave front owing to variations in the water depth along a coastline.</p>
|
||
</dd>
|
||
<dt id="term-relaxation-theory">relaxation theory<a class="headerlink" href="#term-relaxation-theory" title="Permalink to this term">¶</a></dt><dd><p>A concept in which radiated seismic energy is released from stored strain energy
|
||
during the slip along a fault until the adjacent fault blocks reach a new state of equilibrium.</p>
|
||
</dd>
|
||
<dt id="term-residual">residual<a class="headerlink" href="#term-residual" title="Permalink to this term">¶</a></dt><dd><ol class="arabic simple">
|
||
<li><p>The difference between the measured and predicted values of some quantity (e.g., theoretical
|
||
and measured phase arrival time).</p></li>
|
||
<li><p>Attribute of QuakeML object Arrival, see <a class="reference internal" href="#term-arrival"><span class="xref std std-term">arrival</span></a>.</p></li>
|
||
</ol>
|
||
</dd>
|
||
<dt id="term-Ring-of-Fire">Ring of Fire<a class="headerlink" href="#term-Ring-of-Fire" title="Permalink to this term">¶</a></dt><dd><p>The zone of volcanoes and earthquakes surrounding the Pacific Ocean which is called
|
||
the Circum-Pacific belt; about 90% of the world’s earthquakes occur there. The next
|
||
most seismic region (5 - 6 % of earthquakes) is the Alpide belt.</p>
|
||
</dd>
|
||
<dt id="term-RMS">RMS<a class="headerlink" href="#term-RMS" title="Permalink to this term">¶</a></dt><dd><p>Abbreviation for <a class="reference internal" href="#term-root-mean-square-RMS"><span class="xref std std-term">root mean square</span></a></p>
|
||
</dd>
|
||
<dt id="term-root-mean-square-RMS">root mean square (RMS)<a class="headerlink" href="#term-root-mean-square-RMS" title="Permalink to this term">¶</a></dt><dd><p>Also referred to as <a class="reference internal" href="#term-RMS"><span class="xref std std-term">RMS</span></a>. A statistical measure of the magnitude of a varying quantity defined as</p>
|
||
<div class="math">
|
||
<p><img src="../_images/math/2f6a630b284c6a5d80008de8acea2f431a388d2c.png" alt="RMS = \sqrt{\frac{{x_1}^2 + {x_2}^2 + {x_3}^2 + ... + {x_n}^2}{N}}"/></p>
|
||
</div><p>for the time series with the N elements x<sub>1</sub> to x<sub>n</sub>.</p>
|
||
</dd>
|
||
<dt id="term-rupture-front">rupture front<a class="headerlink" href="#term-rupture-front" title="Permalink to this term">¶</a></dt><dd><p>The instantaneous boundary between the slipping and locked parts of a fault during
|
||
an earthquake. A rupture propagating in one direction on the fault is referred to
|
||
as unilateral. A rupture may radiate outward in a circular manner or it may radiate
|
||
towards the two ends of the fault from an interior point, behavior referred to as
|
||
bilateral.</p>
|
||
</dd>
|
||
<dt id="term-rupture-velocity">rupture velocity<a class="headerlink" href="#term-rupture-velocity" title="Permalink to this term">¶</a></dt><dd><p>The speed at which a rupture front moves across the surface of the fault during
|
||
an earthquake.</p>
|
||
</dd>
|
||
<dt id="term-SCML">SCML<a class="headerlink" href="#term-SCML" title="Permalink to this term">¶</a></dt><dd><p><a class="reference internal" href="#term-SeisComP"><span class="xref std std-term">SeisComP</span></a> Markup Language. SCML is a flavor of <a class="reference external" href="https://quake.ethz.ch/quakeml/">QuakeML</a> and is used by <cite>SeisComP</cite> and by
|
||
products of <a class="reference internal" href="#term-gempa-GmbH"><span class="xref std std-term">gempa GmbH</span></a> for exchange. For details read the
|
||
<a class="reference external" href="https://geofon.gfz-potsdam.de/_uml/">UML diagram</a>.</p>
|
||
</dd>
|
||
<dt id="term-SDS">SDS<a class="headerlink" href="#term-SDS" title="Permalink to this term">¶</a></dt><dd><p><cite>SeisComP</cite> Data Structure which is used for archiving waveform data. Below the
|
||
base directory of the archive the SDS has the structure:</p>
|
||
<div class="highlight-sh notranslate"><div class="highlight"><pre><span></span>archive
|
||
<span class="w"> </span>+<span class="w"> </span>year
|
||
<span class="w"> </span>+<span class="w"> </span>network<span class="w"> </span>code
|
||
<span class="w"> </span>+<span class="w"> </span>station<span class="w"> </span>code
|
||
<span class="w"> </span>+<span class="w"> </span>channel<span class="w"> </span>code
|
||
<span class="w"> </span>+<span class="w"> </span>one<span class="w"> </span>file<span class="w"> </span>per<span class="w"> </span>day<span class="w"> </span>and<span class="w"> </span>location,<span class="w"> </span>e.g.<span class="w"> </span>NET.STA.LOC.CHAN.D.YEAR.DOY
|
||
</pre></div>
|
||
</div>
|
||
</dd>
|
||
<dt id="term-SED">SED<a class="headerlink" href="#term-SED" title="Permalink to this term">¶</a></dt><dd><p>Specific Energy Density</p>
|
||
</dd>
|
||
<dt id="term-SeedLink">SeedLink<a class="headerlink" href="#term-SeedLink" title="Permalink to this term">¶</a></dt><dd><p>SeedLink <span id="id12">[<a class="reference internal" href="references.html#id253" title="seedlink. Real-time waveform server. URL: https://docs.gempa.de/seiscomp/current/apps/seedlink.html.">30</a>]</span> is a
|
||
real-time data acquisition protocol and a client-server software that
|
||
implements this protocol</p>
|
||
</dd>
|
||
<dt id="term-SeisComP">SeisComP<a class="headerlink" href="#term-SeisComP" title="Permalink to this term">¶</a></dt><dd><p>SeisComP is likely the most widely distributed software package for
|
||
seismological data acquisition and real-time data exchange over internet.
|
||
Its data transmission protocol SeedLink became a de facto world standard.
|
||
The first version of SeisComP was developed for the <a class="reference external" href="http://geofon.gfz-potsdam.de/geofon/">GEOFON</a> network and further extended
|
||
within the MEREDIAN project under the lead of <a class="reference external" href="http://geofon.gfz-potsdam.de/geofon/">GEOFON</a>/<a class="reference external" href="http://www.gfz-potsdam.de/">GFZ</a> Potsdam and <a class="reference external" href="http://www.orfeus-eu.org/">ORFEUS</a>. Originally SeisComP was designed as a high
|
||
standard fully automatic data acquisition and (near-)real-time data
|
||
processing tool including quality control, event detection and location as
|
||
well as dissemination of event alerts. In the context of the <a class="reference external" href="http://www.gitews.de/">GITEWS</a> project (German Indian Ocean Tsunami Early
|
||
Warning System) additional functionality were implemented to fulfill the
|
||
requirements of 24/7 early warning control centers. Major changes in the
|
||
architecture of SeisComP were necessary and many new features result in
|
||
the upgrade of SeisComP to version 3. Important SeisComP releases are
|
||
shown below. A first prototype of <a class="reference internal" href="#term-SeisComP3"><span class="xref std std-term">SeisComP3</span></a> developed by the
|
||
GITEWS/GEOFON development group was released in May 2007.</p>
|
||
</dd>
|
||
<dt id="term-SeisComP3">SeisComP3<a class="headerlink" href="#term-SeisComP3" title="Permalink to this term">¶</a></dt><dd><p>A previous version of <a class="reference internal" href="#term-SeisComP"><span class="xref std std-term">SeisComP</span></a>.</p>
|
||
</dd>
|
||
<dt id="term-seismic-array">seismic array<a class="headerlink" href="#term-seismic-array" title="Permalink to this term">¶</a></dt><dd><p>An ordered arrangement of seismometers with central data acquisition specially
|
||
designed to analyze seismic signal based on coherent phases. A seismic array
|
||
differs from a local network of seismic stations mainly by the techniques
|
||
used for data analysis. Often, a seismic array are referred to as <a class="reference internal" href="#term-array"><span class="xref std std-term">array</span></a>.</p>
|
||
</dd>
|
||
<dt id="term-seismic-gap">seismic gap<a class="headerlink" href="#term-seismic-gap" title="Permalink to this term">¶</a></dt><dd><p>A section of a fault that has produced earthquakes in the past but is now quiet.
|
||
For some seismic gaps, no earthquakes have been observed historically, but it is
|
||
believed (based on some other methods, such as plate-motion information, strain
|
||
measurements or geological observations) that the fault segment is capable of
|
||
producing earthquakes. A long-term seismic gap may give hint to the most probable
|
||
location of a strong earthquake in the future.</p>
|
||
</dd>
|
||
<dt id="term-seismic-moment-M0">seismic moment (M<sub>0</sub>)<a class="headerlink" href="#term-seismic-moment-M0" title="Permalink to this term">¶</a></dt><dd><p>The seismic moment is defined as</p>
|
||
<div class="math">
|
||
<p><img src="../_images/math/8f1708ea69c95606206a9c9491a7664a7d3ebcfc.png" alt="M_0 = \mu D A"/></p>
|
||
</div><p>with μ as rigidity of the rock at the fault, D as averaged displacement on the
|
||
fault and A as fault surface area. For pure shear sources, M<sub>0</sub> equals
|
||
the <a class="reference internal" href="#term-total-seismic-moment-MT"><span class="xref std std-term">total seismic moment (MT)</span></a>.
|
||
The seismic moment can be related to the released seismic energy ES that is
|
||
proportional to the stress drop Δσ:</p>
|
||
<div class="math">
|
||
<p><img src="../_images/math/045405e3ed4451fb8c73dfa60cf0db9d9c09b15e.png" alt="E_S \approx 0.5 \Delta\sigma D A"/></p>
|
||
</div><p>Rearranging both equations yields to:</p>
|
||
<div class="math">
|
||
<p><img src="../_images/math/bfb9920a001f8f2088e3444b21712bc8ce7eea27.png" alt="E_S \approx \frac{\Delta\sigma}{2\mu} M_0"/></p>
|
||
</div><p>M<sub>0</sub> can be determined by the asymptote of the amplitude spectrum at
|
||
frequency = 0.
|
||
A common technique for determination of the seismic moment M<sub>0</sub> is the
|
||
moment tensor inversion. Assuming reasonable values for the rigidity of the
|
||
rock (3-6 x 104 MPa in crust and upper mantle) and the stress drop (2-6 MPa)
|
||
the seismic moment can be related to the surface wave magnitude Ms by the
|
||
empirical relationship found by <span id="id14">Gutenberg and Richter [<a class="reference internal" href="references.html#id36" title="B. Gutenberg and C.F. Richter. Magnitude and Energy of Earthquakes. Annals of Geophysics, 9(1):1 - 15, 1956. URL: https://resolver.caltech.edu/CaltechAUTHORS:20140130-105324849, doi:10.4401/ag-5590.">43</a>]</span> (units in cgs):</p>
|
||
<div class="math">
|
||
<p><img src="../_images/math/d7e59ce0e8d9250bee9b829d4a243edee8473113.png" alt="\log E_S = 11.8 + 1.5 Ms
|
||
|
||
\log M_0 = 1.5 Ms + 16.1"/></p>
|
||
</div></dd>
|
||
<dt id="term-seismic-network">seismic network<a class="headerlink" href="#term-seismic-network" title="Permalink to this term">¶</a></dt><dd><p>Group of seismic stations that are deployed as single stations or arrays.</p>
|
||
</dd>
|
||
<dt id="term-seismic-ray">seismic ray<a class="headerlink" href="#term-seismic-ray" title="Permalink to this term">¶</a></dt><dd><p>Vector perpendicular to the wave front pointing into the direction of wave
|
||
propagation and marking behind it the “ray trace”. The propagation of seismic
|
||
waves can be easily modelled as the propagation of seismic rays following
|
||
Snell’s Law. This assumption is a reasonable approximation for high frequency waves.</p>
|
||
</dd>
|
||
<dt id="term-seismic-signal">seismic signal<a class="headerlink" href="#term-seismic-signal" title="Permalink to this term">¶</a></dt><dd><p>A coherent transient waveform radiated from a definite, localized seismic source
|
||
that is usually considered as an useful signal for the location of the source,
|
||
the analysis of the source process and/or of the propagation medium (in contrast to noise).</p>
|
||
</dd>
|
||
<dt id="term-seismic-source">seismic source<a class="headerlink" href="#term-seismic-source" title="Permalink to this term">¶</a></dt><dd><p>A localized area or volume generating coherent, usually transient seismic waveforms,
|
||
such as an earthquake, explosion, vibrator etc.</p>
|
||
</dd>
|
||
<dt id="term-semblance">semblance<a class="headerlink" href="#term-semblance" title="Permalink to this term">¶</a></dt><dd><p>Normalized <a class="reference internal" href="#term-beam-power"><span class="xref std std-term">beam power</span></a>.</p>
|
||
</dd>
|
||
<dt id="term-signal-to-noise-ratio">signal-to-noise ratio<a class="headerlink" href="#term-signal-to-noise-ratio" title="Permalink to this term">¶</a></dt><dd><p>The comparison between the amplitude of the seismic signal and the amplitude of
|
||
the noise; abbreviated as <a class="reference internal" href="#term-SNR"><span class="xref std std-term">SNR</span></a>.</p>
|
||
</dd>
|
||
<dt id="term-slab">slab<a class="headerlink" href="#term-slab" title="Permalink to this term">¶</a></dt><dd><p>Usually, the part of the <a class="reference internal" href="#term-lithosphere"><span class="xref std std-term">lithospheric</span></a>
|
||
plate that is underthrusting in a subduction zone and is
|
||
consumed by the Earth’s mantle is called slab.</p>
|
||
</dd>
|
||
<dt id="term-slab-pull">slab pull<a class="headerlink" href="#term-slab-pull" title="Permalink to this term">¶</a></dt><dd><p>The force of gravity causing the cooler and denser oceanic <a class="reference internal" href="#term-slab"><span class="xref std std-term">slab</span></a> to sink
|
||
into the
|
||
hotter and less dense mantle material. The downdip component of this force leads
|
||
to downdip extensional stress in the slab and may produce earthquakes within the
|
||
subducted slab. Slab pull may also contribute to stress on the subduction thrust
|
||
fault if the fault is locked.</p>
|
||
</dd>
|
||
<dt id="term-slip">slip<a class="headerlink" href="#term-slip" title="Permalink to this term">¶</a></dt><dd><p>The relative displacement of formerly adjacent points on opposite sides of a fault.</p>
|
||
</dd>
|
||
<dt id="term-slip-model">slip model<a class="headerlink" href="#term-slip-model" title="Permalink to this term">¶</a></dt><dd><p>A kinematic model that describes the amount, distribution, and timing of a slip
|
||
associated with an earthquake.</p>
|
||
</dd>
|
||
<dt id="term-slip-rate">slip rate<a class="headerlink" href="#term-slip-rate" title="Permalink to this term">¶</a></dt><dd><p>How fast the two sides of a fault are slipping relative to one another, as
|
||
derived from seismic records in case of an earthquake or determined, as a
|
||
long-term average, from geodetic measurements, from offset man-made structures,
|
||
or from offset geologic features whose age can be estimated. It is measured
|
||
parallel to the predominant slip direction or estimated from the vertical or
|
||
horizontal offset of geologic markers.</p>
|
||
</dd>
|
||
<dt id="term-slowness">slowness<a class="headerlink" href="#term-slowness" title="Permalink to this term">¶</a></dt><dd><p>The inverse of velocity, given in the unit seconds/degree or s/km; a large
|
||
slowness corresponds to a low velocity.</p>
|
||
</dd>
|
||
<dt id="term-SNR">SNR<a class="headerlink" href="#term-SNR" title="Permalink to this term">¶</a></dt><dd><p>Abbreviation for <a class="reference internal" href="#term-signal-to-noise-ratio"><span class="xref std std-term">signal-to-noise ratio</span></a>.</p>
|
||
</dd>
|
||
<dt id="term-source-depth">source depth<a class="headerlink" href="#term-source-depth" title="Permalink to this term">¶</a></dt><dd><p>Location of an earthquake below the Earth’s surface. Earthquakes can occur
|
||
between the surface and depths of about 700 km. Usually three classes of
|
||
earthquakes are separated according to the depth: Shallow earthquakes occur
|
||
in the depth range of 0 to 70 km; intermediate earthquakes between 70 and 300km
|
||
depth; and deep earthquakes between 300 and 700 km depth. Earthquakes at large
|
||
depths occur much less frequent than shallow earthquakes. Additionally, deep
|
||
earthquakes excite small surface waves compared to the body waves and relatively
|
||
simple P and S waveforms with more impulsive onsets. A more reliable way to
|
||
determine the depth of an earthquake is to identify depth phases (e.g. pP, sP)
|
||
in the waveforms. At stations with large distance to the epicenter the pP wave
|
||
follows the direct P wave by a time interval that slightly increases with distance
|
||
but rapidly with depth. The depth can be derived from this time interval by using
|
||
<a class="reference internal" href="#term-travel-time-curve"><span class="xref std std-term">travel-time curves</span></a>.</p>
|
||
</dd>
|
||
<dt id="term-source-time-function">source time function<a class="headerlink" href="#term-source-time-function" title="Permalink to this term">¶</a></dt><dd><p>The source time function describes the ground motion generated at the fault over
|
||
time. The function is predicted by a theoretical model.</p>
|
||
</dd>
|
||
<dt id="term-Spooler">Spooler<a class="headerlink" href="#term-Spooler" title="Permalink to this term">¶</a></dt><dd><p>Application which watches a directory for new bulletins and performs the
|
||
final and service specific dissemination operation. This may involve
|
||
talking to modem (for fax, SMS), connecting to a SMTP server (email) or
|
||
rendering a Web page.</p>
|
||
</dd>
|
||
<dt id="term-station">station<a class="headerlink" href="#term-station" title="Permalink to this term">¶</a></dt><dd><p>Site of measurement typically consisting of one or more sensors and one or
|
||
more dataloggers.</p>
|
||
</dd>
|
||
<dt id="term-station-magnitude">station magnitude<a class="headerlink" href="#term-station-magnitude" title="Permalink to this term">¶</a></dt><dd><ol class="arabic simple">
|
||
<li><p>The station magnitude is the magnitude value based on the amplitude measurements of a single station.
|
||
Due to radiation pattern, site and path effects and the calibration of the station the station magnitudes
|
||
of one event can scatter significantly.</p></li>
|
||
<li><p>QuakeML object</p></li>
|
||
</ol>
|
||
</dd>
|
||
<dt id="term-stick-slip">stick-slip<a class="headerlink" href="#term-stick-slip" title="Permalink to this term">¶</a></dt><dd><p>The rapid displacement that occurs between two sides of a fault when the shear stress
|
||
on the fault exceeds the frictional stress. Also a jerky, sliding type of motion
|
||
associated with fault movement in laboratory experiments. It may be a mechanism
|
||
in shallow earthquakes. Stick -slip displacement on a fault radiates energy in the
|
||
form of seismic waves.</p>
|
||
</dd>
|
||
<dt id="term-stress-drop">stress drop<a class="headerlink" href="#term-stress-drop" title="Permalink to this term">¶</a></dt><dd><p>The difference between the stress across a fault before and after an earthquake.
|
||
A parameter in many models of the earthquake source that affects the level of
|
||
high-frequency shaking radiated by the earthquake. Commonly stated in units termed
|
||
bars or megapascals (1 bar equals 1 kg/cm², and 1 megapascal equals 10 bars).</p>
|
||
</dd>
|
||
<dt id="term-T">T<a class="headerlink" href="#term-T" title="Permalink to this term">¶</a></dt><dd><p>period, time duration</p>
|
||
</dd>
|
||
<dt id="term-takeoff-angle">takeoff angle<a class="headerlink" href="#term-takeoff-angle" title="Permalink to this term">¶</a></dt><dd><p>The angle that a seismic ray makes with a downward vertical axis through the
|
||
source. Rays with takeoff angles less than 90° are labeled with capital letters
|
||
like P or S. If the takeoff angle is greater than 90° the ray is upgoing and is
|
||
labeled with lowercase letters (p or s). Such rays can be reflected at the
|
||
surface near the epicenter forming a depth phase (see <a class="reference internal" href="#term-pP-phase"><span class="xref std std-term">pP phase</span></a> or <a class="reference internal" href="#term-sP-phase"><span class="xref std std-term">sP phase</span></a>).</p>
|
||
</dd>
|
||
<dt id="term-teleseismic">teleseismic<a class="headerlink" href="#term-teleseismic" title="Permalink to this term">¶</a></dt><dd><p>Pertaining to a seismic source at distances greater than about 2000 km from the
|
||
measurement site.</p>
|
||
</dd>
|
||
<dt id="term-theoretical-onset">theoretical onset<a class="headerlink" href="#term-theoretical-onset" title="Permalink to this term">¶</a></dt><dd><p>The point where an arrival is expected to appear on a seismic record, based
|
||
on the known location and depth of the seismic source and according to a velocity
|
||
model.</p>
|
||
</dd>
|
||
<dt id="term-time-domain">time domain<a class="headerlink" href="#term-time-domain" title="Permalink to this term">¶</a></dt><dd><p>A seismic record is usually presented in the time domain, i.e., as a display of
|
||
varying amplitudes of (filtered) ground motion as a function of time (in contrast
|
||
to the equivalent representation in the frequency domain) (see also Fourier analysis).</p>
|
||
</dd>
|
||
<dt id="term-Tp">Tp<a class="headerlink" href="#term-Tp" title="Permalink to this term">¶</a></dt><dd><p>predominant period</p>
|
||
</dd>
|
||
<dt id="term-Tm">Tm<a class="headerlink" href="#term-Tm" title="Permalink to this term">¶</a></dt><dd><p>mean period</p>
|
||
</dd>
|
||
<dt id="term-total-seismic-moment-MT">total seismic moment (MT)<a class="headerlink" href="#term-total-seismic-moment-MT" title="Permalink to this term">¶</a></dt><dd><p>A measure of the strength of the full <a class="reference internal" href="#term-moment-tensor"><span class="xref std std-term">moment tensor</span></a>:</p>
|
||
<div class="math">
|
||
<p><img src="../_images/math/1712005c894ef6c6244697d1123cc2c090368cb3.png" alt="M_T = \sqrt{\sum_{ij}M_{ij}M_{ij}/2}"/></p>
|
||
</div><p>For pure shear sources M<sub>T</sub> equals <a class="reference internal" href="#term-seismic-moment-M0"><span class="xref std std-term">seismic moment (M0)</span></a>.</p>
|
||
</dd>
|
||
<dt id="term-transfer-function">transfer function<a class="headerlink" href="#term-transfer-function" title="Permalink to this term">¶</a></dt><dd><p>The transfer function of a seismic sensor-recorder system (or of the Earth
|
||
medium through which seismic waves propagate) describes the frequency-dependent
|
||
amplification, damping and phase distortion of seismic signals by a specific
|
||
sensor-recorder (or medium). The modulus (real term = absolute value) of the
|
||
transfer function is termed the frequency response function or magnification
|
||
curve, e.g. of a seismograph.</p>
|
||
</dd>
|
||
<dt id="term-travel-time">travel time<a class="headerlink" href="#term-travel-time" title="Permalink to this term">¶</a></dt><dd><p>The time required for a wave traveling from its source to a point of observation.</p>
|
||
</dd>
|
||
<dt id="term-travel-time-curve">travel-time curve<a class="headerlink" href="#term-travel-time-curve" title="Permalink to this term">¶</a></dt><dd><p>A graph of arrival times, commonly of direct as well as multiply reflected and
|
||
converted <a class="reference internal" href="#term-P-wave"><span class="xref std std-term">P</span></a> or <a class="reference internal" href="#term-S-wave"><span class="xref std std-term">S waves</span></a>, recorded at different
|
||
points as a function of distance
|
||
from the seismic source. Seismic velocities within the Earth can be computed
|
||
from the slopes of the resulting curves.</p>
|
||
</dd>
|
||
<dt id="term-XXL-event">XXL event<a class="headerlink" href="#term-XXL-event" title="Permalink to this term">¶</a></dt><dd><p>An event based on <a class="reference internal" href="#term-XXL-pick"><span class="xref std std-term">XXL picks</span></a>.</p>
|
||
</dd>
|
||
<dt id="term-XXL-pick">XXL pick<a class="headerlink" href="#term-XXL-pick" title="Permalink to this term">¶</a></dt><dd><p>Picks that have extraordinarily large amplitudes and large <a class="reference internal" href="#term-SNR"><span class="xref std std-term">SNR</span></a> and
|
||
that lie within a relatively small region.</p>
|
||
</dd>
|
||
<dt id="term-vespagram">vespagram<a class="headerlink" href="#term-vespagram" title="Permalink to this term">¶</a></dt><dd><p>Vespagrams are diagrams of <a class="reference internal" href="#term-beam"><span class="xref std std-term">beam</span></a> traces over time typically formed
|
||
for a particular <a class="reference internal" href="#term-azimuth"><span class="xref std std-term">azimuth</span></a> (or <a class="reference internal" href="#term-backazimuth"><span class="xref std std-term">backazimuth</span></a>) and for
|
||
ranges of <a class="reference internal" href="#term-slowness"><span class="xref std std-term">slowness</span></a> (slowness vespagram). When the slowness
|
||
is kept constant and the backazimuth is varied the term backazimuth
|
||
vespagram is used.</p>
|
||
</dd>
|
||
<dt id="term-Wadati-Benioff-zone">Wadati-Benioff zone<a class="headerlink" href="#term-Wadati-Benioff-zone" title="Permalink to this term">¶</a></dt><dd><p>A dipping planar (flat) zone of earthquakes that is produced by the interaction
|
||
of a downgoing oceanic crustal plate with a continental plate. These earthquakes
|
||
can be produced by slip along the subduction thrust fault (thrust interface between
|
||
the continental and the oceanic plate) or by slip on faults within the downgoing
|
||
plate as a result of bending and extension as the plate is pulled into the mantle.
|
||
Slip may also initiate between adjacent segments of downgoing plates. Wadati-Benioff
|
||
zones are usually well-developed along the trenches of the Circum-Pacific belt,
|
||
dipping towards the continents.</p>
|
||
</dd>
|
||
<dt id="term-wave-number">wave number<a class="headerlink" href="#term-wave-number" title="Permalink to this term">¶</a></dt><dd><p>Number of cycles of a repeating signal per unit length, typically per meter of kilometer.</p>
|
||
</dd>
|
||
<dt id="term-P-wave">P wave<a class="headerlink" href="#term-P-wave" title="Permalink to this term">¶</a></dt><dd><p>P (primary) waves are compressional waves involving volumetric variations in the
|
||
media. The sense of particle motion is linear and parallel to the propagation
|
||
direction. P waves are body waves that traverse the interior of a body/Earth and
|
||
can propagate in fluids.</p>
|
||
<p>The general nomenclature for P waves: At local and
|
||
regional distances a special nomenclature is used to describe the travel path of
|
||
the first P and S arrivals. Pg, Pb/P* and Pn phases are separated. Pg is the direct
|
||
P wave arriving first in distances less than around 100 km. Pn is the head wave
|
||
along the Moho arriving first at larger distances than 100 km (depending on the
|
||
crustal thickness). Pn has usually smaller amplitudes than Pg. Pb or P* is the
|
||
rarely observed head wave travelling along the midcrustal velocity discontinuity.
|
||
The general nomenclature of P waves entitles reflections at the topside of boundaries
|
||
with lowercase letters (m – Moho reflection; c - CMB reflection; i - inner core-outer
|
||
core boundary reflection), e.g. PmP is a reflected P wave at the Moho. Reflections
|
||
at the bottom side of boundaries get no additional letter, e.g. PP is a reflected
|
||
P wave at the Earth’s surface. Refracted rays get capital letters (K - through
|
||
the outer core; I - through the inner core), e.g. PKIKP is a P wave traversing
|
||
the crust/mantle, the outer core, the inner core, again the outer core and again
|
||
the mantle/crust.</p>
|
||
</dd>
|
||
<dt id="term-S-wave">S wave<a class="headerlink" href="#term-S-wave" title="Permalink to this term">¶</a></dt><dd><p>S (secondary) waves are shear waves without any volumetric variation in the media.
|
||
The sense of particle motion is perpendicular to the propagation direction. S waves
|
||
are body waves that traverse the interior of a body but can not propagate in fluids.</p>
|
||
<p>Analog to the P arrivals Sg, Sb/S<sup>*</sup> and Sn arrivals are distinguished in local
|
||
and regional distances. The general nomenclature of S waves is analog to the P waves.
|
||
The reflections at the topside of boundaries have lowercase letters (m - Moho
|
||
reflection; c - CMB reflection), e.g. SmS is a reflected S wave at the Moho.
|
||
Reflections at the bottom side of boundaries get no additional letter, e.g. SS is a
|
||
reflected S wave at the Earth’s surface. Refracted rays get capital letters (J - through
|
||
the inner core), e.g. SKJKS is a S wave traversing the crust/mantle, the outer core
|
||
as a <a class="reference internal" href="#term-P-wave"><span class="xref std std-term">P wave</span></a>, the inner core as a <a class="reference internal" href="#term-S-wave"><span class="xref std std-term">S wave</span></a>, again the outer core as a P wave and again
|
||
the mantle/crust as S wave. S waves can not travel through the outer core because
|
||
the outer core consists of a fluid.</p>
|
||
</dd>
|
||
<dt id="term-surface-wave">surface wave<a class="headerlink" href="#term-surface-wave" title="Permalink to this term">¶</a></dt><dd><p>Surface waves are seismic waves observed only at the free surface of the media.
|
||
Two types of surface waves are distinguished: <a class="reference internal" href="#term-Love-wave"><span class="xref std std-term">Love waves</span></a> (L)
|
||
and <a class="reference internal" href="#term-Rayleigh-wave"><span class="xref std std-term">Rayleigh waves</span></a> (R).
|
||
Both result from the interaction of P and S waves near the free surface.</p>
|
||
</dd>
|
||
<dt id="term-waveform-data">waveform (data)<a class="headerlink" href="#term-waveform-data" title="Permalink to this term">¶</a></dt><dd><p>The complete analog or sufficiently dense sampled digital representation of a
|
||
continuous wave group (e.g., of a seismic phase) or of a whole wave train
|
||
(seismogram). Accordingly, waveform data allow to reconstruct and analyze the
|
||
whole seismic phase or earthquake record both in the time and frequency domain
|
||
whereas parameter data describe the signal only by a very limited number of more
|
||
or less representative measurements such as onset time, maximum signal amplitude
|
||
and related period.</p>
|
||
</dd>
|
||
<dt id="term-waveformID">waveformID<a class="headerlink" href="#term-waveformID" title="Permalink to this term">¶</a></dt><dd><p>Attribute of the QuakeML objects Pick, !StationAmplitude and !StationMagnitude
|
||
describing the source of the underlying waveform source. The WaveformID contains
|
||
information about the !NetworkCode, !StationCode, !LocationCode and !ChannelCode</p>
|
||
</dd>
|
||
<dt id="term-wave-front">wave front<a class="headerlink" href="#term-wave-front" title="Permalink to this term">¶</a></dt><dd><p>The surface formed by all elements of a propagating wave, which swing in phase;
|
||
the wave front is perpendicular to the seismic rays, which are oriented in
|
||
direction of wave propagation.</p>
|
||
</dd>
|
||
<dt id="term-wavelength">wavelength<a class="headerlink" href="#term-wavelength" title="Permalink to this term">¶</a></dt><dd><p>The distance between successive points of equal amplitude and phase on a
|
||
wave (for example, crest to crest or trough to trough).</p>
|
||
</dd>
|
||
<dt id="term-weight">weight<a class="headerlink" href="#term-weight" title="Permalink to this term">¶</a></dt><dd><p>Attribute of the QuakeML objects Arrival and !MagnitudeReferences defining the
|
||
effect of the referenced object (e.g. Pick).</p>
|
||
</dd>
|
||
<dt id="term-Wood-Anderson-seismometer">Wood-Anderson seismometer<a class="headerlink" href="#term-Wood-Anderson-seismometer" title="Permalink to this term">¶</a></dt><dd><p>Torsion seismometer recording horizontal displacement
|
||
<a class="reference internal" href="#term-amplitude"><span class="xref std std-term">amplitudes</span></a> described in <span id="id15">Richter [<a class="reference internal" href="references.html#id62" title="C.F. Richter. An instrumental earthquake magnitude scale. Bull. Seismol. Soc. Am., 1:1 - 32, 1935. URL: https://resolver.caltech.edu/CaltechAUTHORS:20140804-143558638, doi:10.1785/BSSA0250010001.">57</a>]</span> and
|
||
<span id="id16">Uhrhammer and Collins [<a class="reference internal" href="references.html#id81" title="R.A. Uhrhammer and E.R. Collins. Synthesis of Wood-Anderson seismograms from broadband digital records. Bull. Seismol. Soc. Am., 80(3):702–716, 1990. doi:10.1785/BSSA0800030702.">64</a>]</span>. Simulation of the Wood-Anderson seismometer is
|
||
used for measuring amplitudes for selected <a class="reference internal" href="#term-magnitude"><span class="xref std std-term">magnitudes</span></a>.
|
||
SeisComP3 and SeisComP in versions 4 and 5 have considered Wood-Anderson
|
||
instrument parameters originally published by <span id="id17">Richter [<a class="reference internal" href="references.html#id62" title="C.F. Richter. An instrumental earthquake magnitude scale. Bull. Seismol. Soc. Am., 1:1 - 32, 1935. URL: https://resolver.caltech.edu/CaltechAUTHORS:20140804-143558638, doi:10.1785/BSSA0250010001.">57</a>]</span> with
|
||
gain = 2800, T0 = 0.8 s, h = 0.8. However, updated parameters where
|
||
published by <span id="id18">Uhrhammer and Collins [<a class="reference internal" href="references.html#id81" title="R.A. Uhrhammer and E.R. Collins. Synthesis of Wood-Anderson seismograms from broadband digital records. Bull. Seismol. Soc. Am., 80(3):702–716, 1990. doi:10.1785/BSSA0800030702.">64</a>]</span> with gain = 2080, T0 = 0.8 s,
|
||
h = 0.7. These values were part of the IASPEI Magnitude Working Group
|
||
recommendations of 2011 September 9 and therefore apply by default in later
|
||
versions of SeisComP. With the original set of values
|
||
<span id="id19">[<a class="reference internal" href="references.html#id62" title="C.F. Richter. An instrumental earthquake magnitude scale. Bull. Seismol. Soc. Am., 1:1 - 32, 1935. URL: https://resolver.caltech.edu/CaltechAUTHORS:20140804-143558638, doi:10.1785/BSSA0250010001.">57</a>]</span>, magnitudes are systematically overestimated by 0.13.
|
||
Wood-Anderson seismometers can be simulated by filtering waveforms with
|
||
<a class="reference internal" href="filter-grammar.html#WA" title="WA"><code class="xref py py-func docutils literal notranslate"><span class="pre">WA()</span></code></a>.</p>
|
||
</dd>
|
||
<dt id="term-WWSSN_SP">WWSSN_SP<a class="headerlink" href="#term-WWSSN_SP" title="Permalink to this term">¶</a></dt><dd><p>Short period seismograph with a dominant period of 1 s of the World-Wide
|
||
Standard Seismograph Network (WWSSN). WWSSN_SP instruments can be simulated
|
||
by filtering waveforms with <a class="reference internal" href="filter-grammar.html#WWSSN_SP" title="WWSSN_SP"><code class="xref py py-func docutils literal notranslate"><span class="pre">WWSSN_SP()</span></code></a>.</p>
|
||
</dd>
|
||
<dt id="term-WWSSN_LP">WWSSN_LP<a class="headerlink" href="#term-WWSSN_LP" title="Permalink to this term">¶</a></dt><dd><p>Long period seismograph with a dominant period of 20 s of the World-Wide
|
||
Standard Seismograph Network (WWSSN). WWSSN_LP instruments can be simulated
|
||
by filtering waveforms with <a class="reference internal" href="filter-grammar.html#WWSSN_LP" title="WWSSN_LP"><code class="xref py py-func docutils literal notranslate"><span class="pre">WWSSN_LP()</span></code></a>.</p>
|
||
</dd>
|
||
<dt id="term-XML">XML<a class="headerlink" href="#term-XML" title="Permalink to this term">¶</a></dt><dd><p>Extensible Markup Language a version of which is <a class="reference internal" href="#term-SCML"><span class="xref std std-term">SCML</span></a>.</p>
|
||
</dd>
|
||
</dl>
|
||
<section id="distance-terms">
|
||
<h3>Distance terms<a class="headerlink" href="#distance-terms" title="Permalink to this heading">¶</a></h3>
|
||
<dl class="simple glossary">
|
||
<dt id="term-distance-epicentral">distance, epicentral<a class="headerlink" href="#term-distance-epicentral" title="Permalink to this term">¶</a></dt><dd><p>The epicentral distance is defined as the shortest distance from a seismic
|
||
station or any other site to the epicentre of the seismic event.</p>
|
||
</dd>
|
||
<dt id="term-distance-hypocentral">distance, hypocentral<a class="headerlink" href="#term-distance-hypocentral" title="Permalink to this term">¶</a></dt><dd><p>The hypocentral distance is defined as the shortest distance from a
|
||
seismic station or any other site to the hypocentre of the seismic event.</p>
|
||
</dd>
|
||
</dl>
|
||
</section>
|
||
</section>
|
||
</section>
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<ul>
|
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<li><a class="reference internal" href="#">Glossary</a><ul>
|
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<li><a class="reference internal" href="#scname-terms"><cite>SeisComP</cite> terms</a></li>
|
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<li><a class="reference internal" href="#scientific-and-technical-terms">Scientific and technical terms</a><ul>
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<li><a class="reference internal" href="#distance-terms">Distance terms</a></li>
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