Frequency-dependent attenuation of P and S waves in northeast India

ISSN： 0956-540X

Source： Geophysical Journal International, Vol.183, Iss.2, 2010-11, pp. : 1052-1060

Disclaimer: Any content in publications that violate the sovereignty, the constitution or regulations of the PRC is not accepted or approved by CNPIEC.

Previous Menu Next

Abstract

SUMMARYWe have analysed 202 seismograms recorded at 10 seismic stations in the northeast (NE) India region to infer the frequency-dependent attenuation characteristics of both P and S waves, in the frequency range from 1.5 to 24 Hz and in the distance range from 30 to 100 km. We used extended coda-normalization method to determine the attenuation of P wave (Q⁻¹_P) and S wave (Q⁻¹_S) . The results show that both P and S waves undergo a strong attenuation along ray paths. The values of Q⁻¹_P and Q⁻¹_S , corresponding to spectral amplitude decays, show strong frequency dependence and are expressed as Q⁻¹_P= (0.035 ± 0.014)f^{−(0.96±0.01)} and Q⁻¹_S= (0.014 ± 0.006)f^{−(0.94±0.03)} , respectively, in 1.5–24 Hz. The ratio Q⁻¹_P/Q⁻¹_S is found to be larger than unity for the whole frequency range. The high frequency dependence of both P- and S waves indicate the highest attenuation among the world at lower frequencies.