Attenuation characteristics of seismic body waves for the crust of Lower Siang region of Arunachal Himalaya

Abstract: The seismic wave attenuation characteristics for the crust of Lower Siang region of Arunachal Himalaya have been investigated using a data set of 104 local earthquakes. The frequency dependence relationships of quality factors for P-wave (Q?) and S wave (Q?) have been estimated by using extended coda wave normalization method in the frequency range 1.5 Hz to 24 Hz. The average variation in the estimated value of Q? and Q? are from 49 at 1.5 Hz to 1421 at 24 Hz and 118 at 1.5 Hz to 2335 at 24 Hz respectively. The frequency dependent relations for P and S-waves are (25±3)f(1.24±0.04) and (62±9)f(1.13±0.04) respectively. The value Q? and Q? obtained in the present study are comparable with the other seismically active regions of the world as well as of India. The Q?/Q? ratio is found greater than unity over the entire range of the frequencies which indicates the importance of contribution of the scattering attenuation to the body waves in the study region. Also Q?/Q?>1 indicates that the crust is highly heterogeneous in this region of Himalaya. The estimated S wave attenuation is compared with the coda wave attenuation (Qc) obtained by Kumar et. al., (2014) for this region. The estimated Q? is found less than Qc over entire frequency range which supports the Zeng et al. (1991) model that explained that the Qc contains the combined effect of scattering and intrinsic attenuation. The obtained attenuation relations in the present study will be useful for simulation of strong ground motion and for estimation earthquake source parameters which have been further required for seismic hazard assessments in this region.

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[Rohtash Kumar, S. C. Gupta and Arjun Kumar (2014); Attenuation characteristics of seismic body waves for the crust of Lower Siang region of Arunachal Himalaya Int. J. of Adv. Res. 2 (6). 0] (ISSN 2320-5407). www.journalijar.com

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