Q Anisotropy in the Region of Garhwal Himalaya

Authors

  • 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.

References

Sharma B, Teotia SS, Kumar D, et al. Frequency dependent attenuation of high frequency P and S waves in the upper crust of Garhwal Himalaya, Proceedings of 6th International Conference and Exposition on Petroleum Geophysics, Kolkata 2006.

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Published

2016-12-01

Issue

Vol. 3 No. 3 (2016)

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Articles

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