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Evidence for high velocity in Koyna seismic zone from P‐wave teleseismic imaging

2000; American Geophysical Union; Volume: 27; Issue: 17 Linguagem: Inglês

10.1029/2000gl011490

1944-8007

D. Srinagesh, Sunil Kumar Singh, K. Srinath Reddy, K. S. Prakasam, S. S.,

Seismic Waves and Analysis

Three‐dimensional P‐wave velocity structure of the crust and upper most mantle beneath the Koyna Seismic Zone (KSZ) was determined by inverting 780 P‐wave teleseismic travel times recorded by a 20 station digital network. The velocity image obtained through damped least square was tested for its resolution using checkerboard approach. The results of the inversion show strong lateral velocity variations of 6% to 7% within the study region. A high velocity anomaly (2% to 5%) in the upper and lower crust beneath the KSZ is flanked by lower velocity (−2% to −5%) anomalies on either side. The correlation of high‐velocity with the seismic zone suggests that the earthquakes are occurring in more rigid rocks with increasing ability to store strain energy and release it as brittle failure.