Estimation of Coda Wave Attenuation for the National Capital Region, Delhi, India Using Local Earthquakes |
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Authors: | William K Mohanty Rajesh Prakash G Suresh A K Shukla M Yanger Walling J P Srivastava |
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Institution: | (1) Department of Geology and Geophysics, Indian Institute of Technology, Kharagpur, West Bengal, 721 302, India;(2) India Meteorological Department, Lodhi Road, New Delhi, India;(3) Department of Geology, University of Delhi, Delhi, 110 007, India |
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Abstract: | Attenuation of seismic waves is very essential for the study of earthquake source parameters and also for ground-motion simulations,
and this is important for the seismic hazard estimation of a region. The digital data acquired by 16 short-period seismic
stations of the Delhi Telemetric Network for 55 earthquakes of magnitude 1.5 to 4.2, which occurred within an epicentral distance
of 100 km in an area around Delhi, have been used to estimate the coda attenuation Qc. Using the Single Backscattering Model, the seismograms have been analyzed at 10 central frequencies. The frequency dependence
average attenuation relationship Qc = 142f 1.04 has been attained. Four Lapse-Time windows from 20 to 50 seconds duration with a difference of 10 seconds have been analyzed
to study the lapse time dependence of Qc. The Qc values show that frequency dependence (exponent n) remains similar at all the lapse time window lengths. While the change
in Q0 values is significant, change in Q0 with larger lapsetime reflects the rate of homogeneity at the depth. The variation of Qc indicates a definitive trend from west to east in accordance with the geology of the region. |
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Keywords: | Coda Q Delhi Telemetry Network single backscattering model and lapse time window attenuation seismic hazard |
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