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<section id="magnitudes">
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<span id="concepts-magnitudes"></span><h1>Magnitudes<a class="headerlink" href="#magnitudes" title="Permalink to this heading">¶</a></h1>
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<p>Magnitudes are computed based on amplitudes measured from waveforms. Different
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types of amplitudes and magnitudes are available which are listed in
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<a class="reference internal" href="../../apps/scamp.html#scamp"><span class="std std-ref">scamp</span></a> and <a class="reference internal" href="../../apps/scmag.html#scmag"><span class="std std-ref">scmag</span></a>.</p>
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<section id="amplitudes">
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<h2>Amplitudes<a class="headerlink" href="#amplitudes" title="Permalink to this heading">¶</a></h2>
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<p>Amplitudes can be measured automatically from waveforms</p>
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<ul class="simple">
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<li><p>During phase picking by <a class="reference internal" href="../../apps/scautopick.html#scautopick"><span class="std std-ref">scautopick</span></a> with generally fixed time windows
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due to the absence of knowledge about source parameters or by,</p></li>
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<li><p><a class="reference internal" href="../../apps/scamp.html#scamp"><span class="std std-ref">scamp</span></a> as soon as <a class="reference internal" href="../glossary.html#term-origin"><span class="xref std std-term">origins</span></a> are available. Depending
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on the magnitude type, fixed or distance-dependent time windows apply.</p></li>
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</ul>
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<p>and interactively using <a class="reference internal" href="../../apps/scolv.html#scolv"><span class="std std-ref">scolv</span></a>.</p>
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<section id="instrument-simulation">
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<h3>Instrument simulation<a class="headerlink" href="#instrument-simulation" title="Permalink to this heading">¶</a></h3>
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<p>Amplitude measurements for some magnitude types require or allow the simulation
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of instruments such as <a class="reference internal" href="../filter-grammar.html#WA" title="WA"><code class="xref py py-func docutils literal notranslate"><span class="pre">Wood-Anderson</span> <span class="pre">torsion</span> <span class="pre">seismometers</span></code></a>
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(<span id="id1">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>], 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>), <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> or <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>.
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The calibration parameters describing the Wood-Anderson seismometer are
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configurable in global bindings or global module configuration:
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<a class="reference internal" href="../../apps/global.html#confval-2"><code class="xref std std-confval docutils literal notranslate"><span class="pre">amplitudes.WoodAnderson.gain</span></code></a>, <a class="reference internal" href="../../apps/global.html#confval-3"><code class="xref std std-confval docutils literal notranslate"><span class="pre">amplitudes.WoodAnderson.T0</span></code></a>,
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<a class="reference internal" href="../../apps/global.html#confval-4"><code class="xref std std-confval docutils literal notranslate"><span class="pre">amplitudes.WoodAnderson.h</span></code></a>. Specifically, the difference in magnitude
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due to configuration using original values listed in
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<span id="id2">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 updated ones given in <span id="id3">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>
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result in a constant offset of 0.13 in those magnitudes which apply
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Wood-Anderson simulation, e.g. <a class="reference internal" href="../glossary.html#term-magnitude-local-ML"><span class="xref std std-term">ML</span></a>,
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<a class="reference internal" href="../glossary.html#term-magnitude-local-vertical-MLv"><span class="xref std std-term">MLv</span></a>, <a class="reference internal" href="../glossary.html#term-magnitude-local-custom-MLc"><span class="xref std std-term">MLc</span></a>.</p>
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</section>
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</section>
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<section id="station-magnitudes">
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<h2>Station Magnitudes<a class="headerlink" href="#station-magnitudes" title="Permalink to this heading">¶</a></h2>
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<p>Station magnitudes are computed automatically by <a class="reference internal" href="../../apps/scmag.html#scmag"><span class="std std-ref">scmag</span></a> or interactively
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by <a class="reference internal" href="../../apps/scolv.html#scolv"><span class="std std-ref">scolv</span></a> from measured amplitudes based on distance-dependent
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calibration curves which depend on magnitude type. When computing a set of
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magnitudes in <a class="reference internal" href="../../apps/scolv.html#scolv"><span class="std std-ref">scolv</span></a> which is different from the set configured in
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<a class="reference internal" href="../../apps/scmag.html#scmag"><span class="std std-ref">scmag</span></a>, then scmag may later add the missing magnitudes automatically.
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Magnitude types for which the evaluation status is set to “rejected”, e.g., in
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scolv, will not be recomputed by scmag.</p>
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<section id="station-corrections">
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<span id="concepts-magnitudes-correction"></span><h3>Station corrections<a class="headerlink" href="#station-corrections" title="Permalink to this heading">¶</a></h3>
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<p>Linear station corrections applied to station magnitudes can be configured by
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global <a class="reference internal" href="configuration.html#global-bindings-config"><span class="std std-ref">binding parameters</span></a>:</p>
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<ol class="arabic simple">
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<li><p>Add a magnitude type profile where the name of the profile is the name of the
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magnitude itself,</p></li>
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<li><p>Configure the correction parameters.</p></li>
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</ol>
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<p>When using binding profiles, all referencing stations will be affected equally
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which is typically not intended. In contrast, applying station bindings requires
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to set up many bindings which may not be intended either.</p>
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<p>Therefore, you may add lines to the global module configuration in
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<code class="file docutils literal notranslate"><span class="pre">global.cfg</span></code> where one line corresponds to one station with one magnitude
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and the corresponding correction parameter. The groups and the name of the
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parameters are identical to the global bindings parameters. All lines start with
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“<em>module.trunk</em>”. Example for an offset correction of
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<a class="reference internal" href="../glossary.html#term-magnitude-local-vertical-MLv"><span class="xref std std-term">MLv</span></a> measured station GE.UGM:</p>
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<div class="highlight-properties notranslate"><div class="highlight"><pre><span></span><span class="na">module.trunk.GE.UGM.magnitudes.MLv.offset</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">0.1</span>
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</pre></div>
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</div>
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<div class="admonition note">
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<p class="admonition-title">Note</p>
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<p>The configuration of parameters starting with <em>module.trunk.</em> is not
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supported by <a class="reference internal" href="../../apps/scconfig.html#scconfig"><span class="std std-ref">scconfig</span></a>. All corresponding configurations must be done
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by direclty editing the configuration file, e.g.,
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<code class="file docutils literal notranslate"><span class="pre">seiscomp/etc/global.cfg</span></code>.</p>
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</div>
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</section>
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</section>
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<section id="network-magnitudes">
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<h2>Network Magnitudes<a class="headerlink" href="#network-magnitudes" title="Permalink to this heading">¶</a></h2>
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<p>Network magnitudes are computed automatically by <a class="reference internal" href="../../apps/scmag.html#scmag"><span class="std std-ref">scmag</span></a> or interactively
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by <a class="reference internal" href="../../apps/scolv.html#scolv"><span class="std std-ref">scolv</span></a> from station magnitudes based on averaging station magnitudes.
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The averaging methods applied by <a class="reference internal" href="../../apps/scmag.html#scmag"><span class="std std-ref">scmag</span></a> are configurable by
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<a class="reference internal" href="../../apps/scmag.html#confval-magnitudes.average"><code class="xref std std-confval docutils literal notranslate"><span class="pre">magnitudes.average</span></code></a>. Available are (<span id="id4">Rosenberger and Gasko [<a class="reference internal" href="../references.html#id70" title="J.L. Rosenberger and M. Gasko. Comparing location estimators: trimmed means, medians, and trimean. In D.C. Hoaglin, F. Mosteller, and J.W. Tukey, editors, Understanding Robust and Exploratory Data Analysis, pages 297-336. Wiley, New York, NY, 1983.">59</a>]</span>):</p>
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<ul class="simple">
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<li><p><em>mean</em>: the mean value from all station magnitudes.</p></li>
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<li><p><em>median</em>: the mean value from all station magnitudes.</p></li>
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<li><p><em>trimmedMean(X)</em>: gnores outlier station magnitudes by first removing the
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largest and the smallest <em>X</em> % of the observed values (percentiles). The mean is
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formed from the remaining station magnitudes.</p></li>
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<li><p><em>trimmedMedian(X)</em>: forms the median from all station magnitudes but returns
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the uncertainty by ignoring the largest and the smallest <em>X</em> % station
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magnitudes.</p></li>
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<li><p><em>medianTrimmedMean(X)</em>: returns the mean magnitude from all station magnitudes
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differing less than <em>X</em> magnitudes from the median.</p></li>
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</ul>
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</section>
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<section id="aliases">
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<h2>Aliases<a class="headerlink" href="#aliases" title="Permalink to this heading">¶</a></h2>
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<p>New magnitude types (aliases) can be created based on existing magnitude and
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amplitude types but configured specifically.
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The setup procedure is outlined in the
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<a class="reference internal" href="../tutorials/magnitude-regionalization.html#tutorials-magnitude-aliases"><span class="std std-ref">tutorial on magnitude aliases</span></a>.</p>
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</section>
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<section id="regionalization">
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<span id="concepts-magnitudes-regionalization"></span><h2>Regionalization<a class="headerlink" href="#regionalization" title="Permalink to this heading">¶</a></h2>
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<p>The computation of station magnitudes can be regionalized. This means that for
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a specific region specific conditions apply when computing magnitudes. The
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conditions include any parameter available for configuring a magnitude
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including global binding parameters such as magnitude calibration, distance
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and depth ranges, etc. As an example you may wish to apply different
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attenuation curves for computing MLv magnitudes to earthquakes in Eastern and
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in Western Canada.</p>
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<p>Regionalization is achieved by adding magnitude-type profiles in the magnitudes
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section of global module configuration parameters. Regionalization assumes
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defaults from global bindings but overrides the values when configured. The
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setup procedure including
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<a class="reference internal" href="#concepts-magnitudes-correction"><span class="std std-ref">station corrections</span></a> is outlined in the
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<a class="reference internal" href="../tutorials/magnitude-regionalization.html#tutorials-magnitude-region-aliases"><span class="std std-ref">tutorial on regionalization</span></a>.</p>
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</section>
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<section id="moment-magnitudes">
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<h2>Moment Magnitudes<a class="headerlink" href="#moment-magnitudes" title="Permalink to this heading">¶</a></h2>
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<p>Moment magnitudes can be derived from all other network magnitudes by mapping of
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the original network magnitude, e.g., <em>Mx</em>, to a new moment magnitude <em>Mw(Mx)</em>.</p>
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<p>The mapping function can be configured for all original magnitude types except
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<a class="reference internal" href="../glossary.html#term-magnitude-derived-mB-Mw-mB"><span class="xref std std-term">mB</span></a> and
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<a class="reference internal" href="../glossary.html#term-magnitude-derived-Mwp-Mw-Mwp"><span class="xref std std-term">Mwp</span></a> where the mapping is hardcoded.
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Read the <a class="reference internal" href="../tutorials/magnitude-regionalization.html#tutorials-mags-moment"><span class="std std-ref">tutorial on moment magnitudes</span></a> for the
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configuration.</p>
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</section>
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<section id="summary-magnitude">
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<span id="concepts-magnitudes-summary"></span><h2>Summary Magnitude<a class="headerlink" href="#summary-magnitude" title="Permalink to this heading">¶</a></h2>
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<p>In order to account for different phenomena related to magnitude computation
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including magnitude saturation and application of different magnitude types at
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specific distance and depth ranges of the sources a summary magnitude can be
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computed from network magnitudes by <a class="reference internal" href="../../apps/scmag.html#scmag"><span class="std std-ref">scmag</span></a>. The summary magnitude is
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usually referred to as <em>M</em>. The name is configurable.</p>
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<div class="admonition note">
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<p class="admonition-title">Note</p>
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<p>Station, network and summary magnitudes are contained uniquely in one
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<a class="reference internal" href="../glossary.html#term-origin"><span class="xref std std-term">origin</span></a>.</p>
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</div>
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</section>
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<section id="preferred-magnitude">
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<h2>Preferred Magnitude<a class="headerlink" href="#preferred-magnitude" title="Permalink to this heading">¶</a></h2>
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<p>From the list of computed network magnitudes and the summary magnitude,
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<a class="reference internal" href="../../apps/scevent.html#scevent"><span class="std std-ref">scevent</span></a> can automatically determine the preferred magnitude of the
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<a class="reference internal" href="../glossary.html#term-event"><span class="xref std std-term">event</span></a>. This may also be done interactively by operators in the
|
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<a class="reference internal" href="../../apps/scolv.html#scolv-sec-event-tab"><span class="std std-ref">Event tab of scolv</span></a> or by
|
||
<a class="reference internal" href="../../apps/scolv.html#sec-scolv-custom-commit"><span class="std std-ref">custom commit buttons in scolv</span></a>.</p>
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<h3><a href="../../index.html">Table of Contents</a></h3>
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<ul>
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<li><a class="reference internal" href="#">Magnitudes</a><ul>
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<li><a class="reference internal" href="#amplitudes">Amplitudes</a><ul>
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<li><a class="reference internal" href="#instrument-simulation">Instrument simulation</a></li>
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</ul>
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</li>
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<li><a class="reference internal" href="#station-magnitudes">Station Magnitudes</a><ul>
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<li><a class="reference internal" href="#station-corrections">Station corrections</a></li>
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</ul>
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</li>
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<li><a class="reference internal" href="#network-magnitudes">Network Magnitudes</a></li>
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<li><a class="reference internal" href="#aliases">Aliases</a></li>
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<li><a class="reference internal" href="#regionalization">Regionalization</a></li>
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<li><a class="reference internal" href="#moment-magnitudes">Moment Magnitudes</a></li>
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<li><a class="reference internal" href="#summary-magnitude">Summary Magnitude</a></li>
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<li><a class="reference internal" href="#preferred-magnitude">Preferred Magnitude</a></li>
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</ul>
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