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Q Anisotropy in the Region of Garhwal Himalaya

Gaurav Sharma, Akshat Dimri

Abstract


Empiricalrelations have been found outto describe the decayin amplitude with distance of s-waves in the region of Garhwal Himalaya. These functions results from the analysis of spectral amplitudes of three component digital records from 19 local earthquakes obtained from 12-station seismological network deployed in the Garhwal lesserHimalaya. The events lie in a magnitude range from ML 2 to ML 4.5, epicentral distance 5 to 120 km and focal depth from 5 to 50 km.To determine thevariations of the quality factor Qin the direction of wave propagation (Q anisotropy), independent estimates have been made of the attenuation ofSV- and SH-waves using vertically polarized and transversely polarizedcomponents, respectively. Frequency analyzed (1–12 Hz) and in the whole distance range, the frequency dependence of Q can be approximated as Qsh = 74.3 f 1.0 for the SH-wave and Qsv = 81.5 f 0.95 for the SV-waves.The small difference between SH and SV spectraldecay, suggests that Q anisotropy is negligible. However, in the distance range of 5–50 km, Qsv tends to be significantly greater than Qshat frequency > 8 Hz. So in this distance range we observed Q anisotropy in the studied region. The dependence of Q value with frequency in this range is Qsh = 110 f 0.94 for SH- wave and Qsv = 134 f1.0for SV-waves.

 

Keywords: Velocity, Anisotropy, Frequency, S-wave

Cite this Article

Gaurav Sharma, AkshatDimri. Q Anisotropy in the region of Garhwal Himalaya;Journal of Offshore Structure and Technology. 2016; 3(3): 25–31p.


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References


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