Attenuation Characteristics of Body-Waves for the Bilaspur Region of Himachal Lesser Himalaya

Abstract

The attenuation characteristics around Bilaspur region of the Himachal Lesser Himalaya have been estimated adopting extended-coda-normalization method, and using a data set of 41 local events (0.5 < M L ≤ 2.9) that occurred in the region from May 2013 to March 2014. The frequency-dependent relations governing the quality factors of P-waves (Q α ) and S-waves (Q β ) in the frequency range from 1.5 to 24 Hz are: (Q α ) = (43 ± 4) f 1.30±0.04 and Q β = (79 ± 6) f 1.25±0.02. The average estimates of (Q α ) and (Q β ) are found to vary from 71 and 125 at 1.5 Hz to 2901 and 4243 at 24 Hz, respectively. The (Q α ) and (Q β ) estimates are compared to the similar estimates obtained for the other seismically active regions of the Himalaya. It is found that for the various Himalayan regions, the (Q α ) estimates at 1 Hz vary between 22 (for the Kumaon Himalaya) and 97 (for the northwest Himalaya), whereas (Q β ) estimates range between 63 (for the Garhwal Himalaya) and 127 (for the northwest Himalaya). For the Bilaspur region, the (Q β )/(Q α ) ratio is greater than unity and varies between 1.84 and 1.45 in the frequency range from 1 to 24 Hz. The region-specific attenuation relations can be adopted for estimating earthquake source parameters, simulating strong ground motion and assessing seismic hazard for the Bilaspur region of Himachal Lesser Himalaya.