Temporal changes of subsurface velocities during strong shaking as seen from seismic interferometry

Yamada, Masumi; Mori, Jim; Ohmi, Shiro

doi:10.1029/2009jb006567

Cited by 42 publications

(37 citation statements)

References 16 publications

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“…D(w) is the frequencydomain waveform that propagates from the borehole sensor to the surface sensor [Snieder and Şafak, 2006;Mehta et al, 2007;Sawazaki et al, 2009;Yamada et al, 2010]. We choose to be 1% of the average power spectrum of the wavefield at the borehole receiver because we find experimentally this is the smallest value of the regularization parameter that produces stable deconvolved wavefields.…”

Section: Deconvolution Interferometrymentioning

confidence: 99%

Near-surface weakening in Japan after the 2011 Tohoku-Oki earthquake

Nakata¹,

Snieder

2011

Geophys. Res. Lett.

133

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The magnitude (MW) 9.0 Tohoku‐Oki earthquake on 11 March 2011 was one of the largest in recent history. Ground motion caused by the seismicity around the time of the main shock was recorded by KiK‐net, the strong‐motion network that covers most of Japan. By deconvolving waveforms generated by earthquakes that are recorded at the surface and in a borehole at KiK‐net station FKSH18, we detect a reduction of shear‐wave velocity in the upper 100 m of about 10%, and a subsequent healing that varies logarithmically with time. Using all available borehole and surface records of more than 300 earthquakes that occurred between 1 January 2011 and 26 May 2011, we observe a reduction in the shear‐wave velocity of about 5% in the upper few hundred meters after the Tohoku‐Oki earthquake throughout northeastern Japan. The area of the velocity reduction is about 1,200 km wide, which is much wider than earlier studies reporting velocity reductions following other larger earthquakes. The reduction of the shear‐wave velocity is an indication that the shear modulus, and hence the shear strength, is reduced over a large part of Japan.

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Section: Deconvolution Interferometrymentioning

confidence: 99%

Near-surface weakening in Japan after the 2011 Tohoku-Oki earthquake

Nakata¹,

Snieder

2011

Geophys. Res. Lett.

133

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“…Previous studies extracted time lapse changes caused by earthquakes [Li et al, 1998;Vidale and Li, 2003;Schaff and Beroza, 2004;Wegler and Sens-Schönfelder, 2007;Brenguier et al, 2008]. Interferometry applied to a single KiK-net station has also been used to measure time lapse change due to earthquakes [Sawazaki et al, 2009;Yamada et al, 2010]. Interferometric studies have shown changes in the shear wave velocity caused by precipitation [Sens-Schönfelder and Wegler, 2006] and have measured shear wave splitting [Bakulin and Mateeva, 2008;Miyazawa et al, 2008].…”

Section: Introductionmentioning

confidence: 99%

“…By using these networks for seismic interferometry, Tonegawa et al [2009] extract the deep subsurface structure of the Philippine Sea slab. These data have also been used to observe time lapse changes in small regions [Wegler and Sens-Schönfelder, 2007;Sawazaki et al, 2009;Wegler et al, 2009;Yamada et al, 2010]. Each KiK-net station has two receivers, one on the ground surface and the other at the bottom of a borehole.…”

Section: Introductionmentioning

confidence: 99%

Estimating near‐surface shear wave velocities in Japan by applying seismic interferometry to KiK‐net data

2012

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[1] We estimate shear wave velocities in the shallow subsurface throughout Japan by applying seismic interferometry to the data recorded with KiK-net, a strong motion network in Japan. Each KiK-net station has two receivers; one receiver on the surface and the other in a borehole. By using seismic interferometry, we extract the shear wave that propagates between these two receivers. Applying this method to earthquake-recorded data at all KiK-net stations from 2000 to 2010 and measuring the arrival time of these shear waves, we analyze monthly and annual averages of the near-surface shear wave velocity all over Japan. Shear wave velocities estimated by seismic interferometry agree well with the velocities obtained from logging data. The estimated shear wave velocities of each year are stable. For the Niigata region, we observe a velocity reduction caused by major earthquakes. For stations on soft rock, the measured shear wave velocity varies with the seasons, and we show negative correlation between the shear wave velocities and precipitation. We also analyze shear wave splitting by rotating the horizontal components of the surface sensors and borehole sensors and measuring the dependence on the shear wave polarization. This allows us to estimate the polarization with the fast shear wave velocity throughout Japan. For the data recorded at the stations built on hard rock sites, the fast shear wave polarization directions correlate with the direction of the plate motion.Citation: Nakata, N., and R. Snieder (2012), Estimating near-surface shear wave velocities in Japan by applying seismic interferometry to KiK-net data,

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“…At present, field observations in geophysics have shown that acoustoleastic constant (relative-wave-velocity sensitivity to the initial stresses) of the FSPR is much greater than that of metal materials (Cheng et al, 2010;Nakata and Snieder, 2011;Niu et al, 2008;Sayers, 2010;Tosaya, 1982;Yamada et al, 2010). In addition, acoustoelastic effect of the FSPR has also been verified in rock experiments (Sayers, 2010).…”

Section: Introductionmentioning

confidence: 87%

Acoustoelasticity for a Dissipative Fluid-Saturated Porous Rock

Wang¹,

Dong²,

Tian³

2013

Poromechanics V

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Acoustoelastic theory for a dissipative fluid-saturated porous rock (FSPR) is investigated based on the finite deformation theory of the continuum and poroelastic theory. The assumption of a small dynamic motion superimposed on a largely static pre-deformation of the FSPR yields natural, initial, and final configurations. The consideration of homogeneous pre-deformation, dissipation induced by the Poiseuille-type fluid-solid relative motion, the plane harmonic form of the small dynamic motion according to the constitutive relations and equations of motion of the dissipative FSPR gives acoustoelastic equations, which provide the analytical formulations for the relation of the velocities of the fast longitudinal wave, the fast shear wave, the slow shear wave, and the slow longitudinal wave with the solid-skeleton stresses and the fluid pore-pressure. Taking a rock under open-pore jacketed condition as an example, the detailed discussions about the characteristic of wave dispersion and attenuation for the shear waves are shown that the characteristic of wave dispersion and attenuation for the dissipative FSPR is usually influenced by the pre-deformation. The pre-deformation has little effect on the characteristic of wave dispersion and attenuation for dissipative FSPR only when the components of the applied initial principal stresses are equal.

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Temporal changes of subsurface velocities during strong shaking as seen from seismic interferometry

Cited by 42 publications

References 16 publications

Near-surface weakening in Japan after the 2011 Tohoku-Oki earthquake

Near-surface weakening in Japan after the 2011 Tohoku-Oki earthquake

Estimating near‐surface shear wave velocities in Japan by applying seismic interferometry to KiK‐net data

Acoustoelasticity for a Dissipative Fluid-Saturated Porous Rock

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