Short Period Group Velocity Measurements and Maps in Central Asia
COLORADO UNIV AT BOULDER
Pagination or Media Count:
The purpose of this study is to improve group velocity maps designed to advance the detection and discrimination capabilities for the area encompassed by western China, northern India, and Pakistan. These maps may be used to construct sharply tuned phase-matched filters for extracting weak surface wave signals from background noise and to make better estimates of surface wave spectral magnitudes for small events. We are working now to obtain a greatly expanded data set of short-period measurements 7 - 15 s. We have analyzed seismograms following approximately 1,000 events that occurred in and around the studied region from 1996 - 1999. We obtained about 6,000 short-period dispersion curves for Rayleigh and 4,000 curves for Love waves. We added these measurements to existing dispersion curves and estimated a refined set of dispersion maps on a one-degree grid worldwide. Here we present preliminary refined group velocity maps from 10-s to 18-s periods. Improvements produced by the new data set are mostly at the shorter end of this period band in Central Asia.
- Seismic Detection and Detectors