MLv

MLv is the Richter (1935) magnitude measured on the vertical component.

Description

Amplitude

The MLv amplitude calculation is very similar to the original ML, except that the amplitude is measured on the vertical component.

Station Magnitude

The individual station MLv is calculated up to the epicentral distance maxDistanceKm using the following formula:

MLv = \log10(A) - \log10(A0)

A is the MLv Wood-Anderson amplitude in millimeters. The second term is the empirical calibration function, which in turn is a function of the epicentral distance (see Richter, 1935). This calibration function can be configured globally or per station using the config variable module.trunk.global.MLv.logA0, e.g.

module.trunk.global.MLv.logA0 = "0 -1.3;60 -2.8;100 -3.0;400 -4.5;1000 -5.85"

The logA0 configuration string consists of an arbitrary number of distance-value pairs separated by semicolons. The distance is in km and the value corresponds to the log10(A0) term above.

Within each interval the values are computed by linear interpolation. E.g. for the above default specification, at a distance of 80 km the log10(A0) value would be

\log10(A0) &= ((-3.0)-(-2.8))*(80-60)/(100-60)-2.8 \\
           &= -2.9

In other words, at 80 km distance the magnitude would be

MLv &= \log10(A) - (-2.9) \\
    &= \log10(A) + 2.9

which is according to the original Richter (1935) formula if the amplitude is measured in millimeters.

  • Amplitude unit in SeisComP: millimeter (mm)

  • Time window: 150 s by scautopick or distance dependent

  • Default distance range: 0 - 8 deg

  • Depth range: no limitation

Network magnitude

By default, the trimmed mean is calculated from the station magnitudes to form the network magnitude. Outliers below the 12.5% and above the 12.5% percentiles are removed before the calculation.

Configuration

Several distance-value pairs can be configured for different ranges of epicentral distance. The calibration function and maximum distance can be configured globally, per network or per station using the configuration variables, e.g.

global:

module.trunk.global.MLv.logA0 = "0 -1.3;60 -2.8;400 -4.5;1000 -5.85"
module.trunk.global.MLv.maxDistanceKm = -1

or per network:

module.trunk.GR.MLv.logA0 = "0 -1.3;60 -2.8;400 -4.5;1000 -5.85"
module.trunk.GR.MLv.maxDistanceKm = -1

or per station:

module.trunk.GR.MOX.MLv.logA0 = "0 -1.3;60 -2.8;400 -4.5;1000 -5.85"
module.trunk.GR.MOX.MLv.maxDistanceKm = -1

Set the configuration and calibration parameters in the global bindings. By deault MLv is computed by scautopick and is visible in the GUI.