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Satoh T.,Ohsaki Research Institute Inc. | Okawa I.,Japan Building Research Institute | Nishikawa T.,Tokyo Metroplitan University | Sato T.,Shimizu Corporation
Journal of Structural and Construction Engineering | Year: 2011

We present a new empirical model to spatially interpolate amplification factors of 5 % damped acceleration response spectra obtained at strong motion stations at intervals of about 10 to 20 km for periods ranging from 0.5 to 10 s. The predictor variable is Tz3.2 which is the propagation time of S wave from the seismic bedrock to the engineering bedrock calculated by velocity structure just beneath the station extracted from three-dimensional model with a grid spacing of about 1km. The logarithm of the amplification factors in the Kanto basin, the Nobi basin, and the Osaka basin are modeled by bi-linear regression lines using the Tz3.2. We also interpret the bi-linear regression lines by medium response of surface waves.


Satoh T.,Ohsaki Research Institute Inc. | Okawa I.,Japan Building Research Institute | Nishikawa T.,Tokyo Metroplitan University | Sato T.,Shimizu Corporation
Journal of Structural and Construction Engineering | Year: 2010

We develop empirical regression relations for estimating waveforms of horizontal and vertical ground motions in a period range of 0.1 tol0 seconds caused by subduction-zone and crustal earthquakes using many strong motion records all in Japan. The relations are provided for 5 % and 1 % damped acceleration response spectra, energy spectrum, average of group delay time, and standard deviation of group delay time. The waveforms with site-specific amplification and phase spectra are easily calculated by the empirical relations using the outer-fault parameters, rupture starting points, delay time among rupture starting points, and the location of the strong motion stations in interest. We show that waveforms calculated by the empirical relations for the hypothetical Nankai earthquake are consistent with waveforms calculated by the theoretical method using three dimensional structure model and inner-fault parameters as well as outer-fault parameters in previous studies.


Satoh T.,Ohsaki Research Institute Inc.
Journal of Structural and Construction Engineering | Year: 2010

The Q value and short period source spectra of the 2009 Suruga bay earthquake ({6.5) and its aftershocks are estimated using spectral inversion method. Then the source model composed of two strong motion generation areas (SMGAs) are estimated using the empirical Green's function method. The estimated Q value near the source region is modeled as 30fDM, that is, f is frequency The short period source spectrum of the main shock is the largest among previous intmslab earthquakes occulTed in the Philippine Sea plate and larger than the average value for intraslab earthquakes oceulTed in the Pacific Sea plate. The stress drop and the total area of SMGAs ate estimated to be 751 bar and 18 km2, respectively The stress drop of SMGAs is larger than the empirical scaling law for custal earthquakes and big intractable earthquakes in the Philippine Sea plate. The total area SMGAs is smaller than the empirical scaling law for crystal earthquakes.


Satoh T.,Ohsaki Research Institute Inc.
Journal of Structural and Construction Engineering | Year: 2010

Empirical relations between short-period source spectra and seismic moment for dip-slip and strike-slip crustal earthquakes in Japan, ranging moment magnitude from 5.7 to 6.9, are developed by spectral inversion method using near-fault strong motion records. The short-period source spectrum A for dip-slip earthquakes is 1.45 times of A by Dan et al.'s empirical relation for crustal earthquakes in the world. The A for strike-slip earthquakes is 0.64 times of A by Dan et al.'s relation. The A calculated from previous source models estimated by empirical Green's function method has the similar trend. The combined asperity area of the previous source models has no differences between dip-slip and strike-slip crustal earthquakes and is 0.8 times of Somerville et al. 's relation for crustal earthquakes in the world. On the other hand, the A for interplate earthquakes in eastern Japan, ranging moment magnitude from 6.6 to 8.2, estimated by spectral inversion method in previous studies is found to be 1.63 times of A by Dan et al.'s relation.


Satoh T.,Ohsaki Research Institute Inc. | Okawa I.,Japan Building Research Institute | Sato T.,Shimizu Corporation | Tohdo M.,Ohsaki Research Institute Inc. | Nishikawa T.,Tokyo Metroplitan University
Journal of Structural and Construction Engineering | Year: 2014

Long-period ground motions for the Nankai Trough mega-earthquakes are predicted using our empirical relations for 5 % damped acceleration response spectra and group delay time. The predicted waves in the period rage of 0.1 to 10 seconds for the Tonankai earthquake (Mw8.1), the Nankai earthquake (Mw8.4), and the hypothetical mega-earthquake (Mw9.0) are consistent with the previous waves predicted by the other methods if the variations of data and the difference of the methods are taken into account. We also develop empirical models to interpolate site factors obtained at strong motion stations at intervals of about 10 to 20 km in the Kanto basin, the Nobi basin, and the Osaka basin and apply the models for these predictions.

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