Seismic Event Location Strategy and Path Calibration in and Around the Indian Subcontinent
URS GROUP INC PASADENA CA
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The primary objective of this study is to obtain reliable earthquake locations 4Mw6 that occur in and around the Indian subcontinent for reliable calibration parameters for the region. Unlike many other regions of the world, our study region often lacks easy access to local seismic data. Thus, it has become essential to establish a procedure that can be used to improve locations of seismic events that satisfy the ground truth GT25 criteria. To this end, we find that for an event that satisfies GT10 criteria one can remove all the local and regional phase data within 30 degrees and can still produce locations comparable to the GT10 results when the depth is independently determined. For moderate sized events, locations become biased due to the poor azimuthal distribution of seismic stations. This influences the trade-off between the depth and the origin time. We have examined our approach by applying to events whose locations were also determined using synthetic aperture radar interferometry InSAR analysis. We find that seismic locations determined by our approach remained within 5 km of these locations. Though the InSAR locations may not coincide with the dynamic seismic locations for the larger events because of the size of the fault, they are, however, fairly close for moderate sized events Mw 5.5. We have applied this location approach to identify GT10 events that are within 20 degrees of NIL in Pakistan, EVN in Nepal, and COC of Sri Lanka.
- Seismic Detection and Detectors