Frequency-Dependent Attenuation ofPandSWaves In the Kanto Area, Japan, Based On the Coda-Normalization Method

Abstract

S U M M A R YW e propose a new method for the simultaneous measurement of P -and S-wave attentuation by extending the conventional coda-normalization method which had been limited to the estimation of S-wave attenuation. Using this method, we measured frequency-dependent attenuation of both P a n d S waves in the lithosphere beneath the Kanto area, Japan, from seismograms of 174 local earthquakes for the frequency range 1.5 5 f 5 24 Hz. T h e values of Q;' and Q;' corresponding t o peak amplitude decays show strong frequency dependence, a n d are expressed by using power laws Q,' = 0.012f-')73 and Qp' = 0.031f~0Y5, respectively. T h e ratio Qp'/Q.;' is found t o be larger than unity for the whole frequency range. The apparent attenuations of P and S waves with travel distance are almost the same for frequencies higher than 1 Hz. Our results differ from the characteristics of low-frequency wave attenuation reported by other studies for frequencies lower than 1 Hz. This frequency dependence and the ratio may suggest that scattering loss due t o random heterogeneities in the earth medium plays an important role in seismic-wave attenuation in the lithosphere.

Attenuation characteristics, source parameters and site effects from inversion of S waves of the March 31, 2006 Silakhor aftershocks

“…This evaluated apparent Q factor with low Q 0 and value of N near to 1 indicates high attenuation characteristics in this region and is similar to the results have been found for other tectonically active regions of Iran and the world [Rovelli 1982, Hellweg et al 1995, Yoshimoto et al 1993, Castro et al 1996, Bindi et al 2006, Motazedian 2006 amongst others].…”

Determination of Seismic Wave Attenuation for the Garhwal Himalayas, India

“…In order to obtain the direct wave attenuation, CNM developed by [7] and further extended by [9] is used in this work. As the name suggests, in CNM, the coda wave spectra of the seismogram is used in order to normalize the direct wave spectra in order to obtain the direct wave attenuation.…”

“…[7] First developed coda normalization method to obtain S wave attenuation, which was further extended by [9] to obtain P wave attenuation. As per [9], for narrow f and w M range, the ratio of source spectral amplitude of P and S waves ( ) ( )…”

Direct simulation Monte Carlo method with a focal mechanism algorithm

“…In particular, regional information on Q -1 of high-frequency waves in the lithosphere is very helpful, not only for scientific research, but also for the practical purpose of simulating earthquake ground motion in engineering seismology (Yoshimoto et al, 1993). After the observation of lithospheric Q -1 at high frequency (Dainty, 1981), recent regional studies (e.g.…”