Imaging S-wave scatterer distribution in southeast part of the focal area of the 2005 West Off Fukuoka Prefecture Earthquake (MJMA 7.0) by dense seismic array

Abstract

Spatial distribution of S-wave scatterers in the SE part of the focal area of the 2005 West Off Fukuoka Prefecture Earthquake (M = 7.0) has been estimated using dense seismic array data. Waveforms of 22 natural earthquakes were analyzed in a frequency range of 16-24 Hz. It is difficult to estimate the inhomogeneous structure in this wavelength range with ordinary travel time tomography despite the importance of this parameter for understanding the earthquake-generating process. After filtering and gain recovery in the coda part, observed waveforms were semblance-enhanced slant-stacked into various directions from the array. This was followed by diffraction curve summation in order to image the scatterer distribution. The spatial distribution of scatterers thus imaged revealed that higher strengths were distributed at the SE-extension of the fault plane of the event, which corresponds to a region where the rupture process of the main shock stopped.

Modeling heterogeneous deviatoric stress field around the hypocentral area of the 2005 Fukuoka earthquake (M7.0) by spatially distributed moment tensors

“…It relates to the inelastic deformation around the area, suggesting possibility that the medium is heterogeneous there. Matsumoto et al [2006, 2009] revealed that the relative scattering strength and attenuation factor of seismic waves are high around the edge of the fault. Their results demonstrate that the medium in the region also has inelastic property and/or strong heterogeneity with the shorter wavelength than wavelength of the seismic wave around 4–30 Hz.…”

High resolutionQ−1estimation based on extension of coda normalization method and its application toP-wave attenuation structure in the aftershock area of the 2005 West Off Fukuoka Prefecture Earthquake (M7.0)

“…In Fig. 12(c), the scatterer distribution reported by Matsumoto et al (2006) is shown. Based on seismic array observations, they identified relatively strong scatterers using array processing that determines coherent waves in the coda part, yielding the distribution.…”

“…The white contour denotes the slip distribution proposed by Asano & Iwata (2006). (c) Scatterer distribution estimated by Matsumoto et al (2006) based on the seismic array observation. The shaded area denotes the value with low reliability.…”