global Surface wave magnitude measured at around 20 s The surface wave magnitude measured on the vertical component at around 20 s period. Parameters for computing Ms_20 magnitudes from Ms_20 amplitudes. Lower period limit of the signal for computing Ms_20. Upper period limit of the signal for computing Ms_20. Minimum epicentral distance for computing Ms_20. Maximum epicentral distance for computing Ms_20. Maximum depth for computing Ms_20.