Full Moment Tensor Waveform Inversions of Moderate Earthquakes and Seismic Source Categorization
Abstract
The physical characteristics of seismic sources can be inferred from accurate source parameters , which are helpful for seismotectonics, volcanic activities, post-earthquake rescues and tsunami warning. After the moderate or devastating earthquakes occurred(Mw>5.0), it is routine to determine the source parameters based on point source approximation,including earthquake locations, magnitudes, depths, moment tensors, etc.
The gCAP (generalized Cut and Paste) waveform inversion method could combine body waves and surface waves of local broadband seismic stations (Epicentral distance <5°) to resolve the source parameters after the earthquakes rapidly and suppress the effects of heterogeneous efficiently. On the global scale, the occurrence and distribution of moderate earthquakes (Mw5.0 7.0) are more frequently and widely than strong earthquakes (Mw>7.0). However, when seismic network is sparse, the measurement of moment tensors are often affected by the insufficient data of local seismic stations, so it's necessary to combine with teleseismic (Epicentral distance 30° 90°) stations for joint inversion. Recently, more and more researchers have used the non-DC source mechanism to study earthquakes in different tectonic settings. But the different definitions and representations adopted by researchers often make the results inconsistent with each other. It is useful to perform joint inversion and expand the representation of seismic source types so as to distinguish the source types more directly. In order to improve moment tensor determination of moderate earthquakes, we present a procedure called gCAPjoint-STS(source types) to jointly invert for source parameters with local and teleseismic broadband seismic waveforms. If Green function are calculated using a 3D velocity model, the procedure will be also appropriate for the 3D source parameters inversion. For the purpose of making a comparative analysis of different seismic source types (ISO, CLVD, DC), various source categorization methods are provided. The influence of velocity structure, station distribution and earthquake locations on the measurement of source depth and moment tensor are also estimated. We apply this procedure to determine source parameters of shallow and deep earthquakes in Pamirs Plateau.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.S21C0455B
- Keywords:
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- 7215 Earthquake source observations;
- SEISMOLOGYDE: 7230 Seismicity and tectonics;
- SEISMOLOGYDE: 8123 Dynamics: seismotectonics;
- TECTONOPHYSICSDE: 8164 Stresses: crust and lithosphere;
- TECTONOPHYSICS