The estimation of layered velocity model by waveform inversion using observed ground motion records is one of ways for modeling deep subsurface structure for the numerical simulation of long-period ground motion. The effectiveness and problem of the estimation by waveform inversion are examined. The numerical test of the waveform inversion using simulated waveform gives good estimation of velocity model assumed beforehand, without constraints of number of layers and velocity of each layers. The case study of application to strong ground motion records at OJIYA, K-NET is conducted. The estimated velocity model by waveform inversion corresponds to the estimated velocity models based on geophysical exploration, geomorphology and geology in previous research. The effect of spatial irregularity of subsurface structure is examined using FDM simulation and waveform inversion. In waveform inversion, the waveform affected by spatial irregularity of subsurface structure gives distorted estimations of the velocity structure. In the region around epicenter, the waveform is not affected by spatial irregularity of subsurface structure so much. In the estimation of velocity model, therefore, the effect of spatial irregularity is small in the region.

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We developed the immediate earthquake intensity information aggregation system using PC built-in sensors and IP multicast. This system detects earthquake motion using the PC built-in acceleration sensor and transmits the information of earthquake motion to other PC using IP multicast communication. This also records earthquake motion at the same time, which will be very useful for firefighters to rescue victims. We confirmed the usability of this system by carrying out the vibration tests.

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Vulnerability functions of buildings are examined based on the damage survey data in seven earthquakes occurred in 2003 to 2008. The building damage ratios show lower correlation with peak acceleration, but higher correlation with instrumental seismic intensity or peak velocity. The obtained vulnerability functions, in comparison with the previous ones based on the data in the 1995 Kobe earthquake, are that 1) the damage ratios increase more rapidly with increase of ground motion intensity, 2) the damage ratios are lower at the same intensity level and 3) the difference of the functions for older and newer buildings is smaller.

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A new method to evaluate relative site amplification factors (RSF) of strong motion sites scattered in a wide area without assumption of attenuation functions is proposed. In this method RSF between adjacent two sites is evaluated by average spectral ratio of strong ground motions simultaneously observed at those two sites. RSF of distant sites are estimated by least squares method, combining RSF of adjacent sites in the network consists of adjacent site pairs in the area. This method is applied to K-NET and KiK-net sites in the Pacific coast side of Tohoku district. Evaluated RSF between adjacent sites are interpreted by theoretical amplification factors based on one dimensional wave theory. Relations of the evaluated RSF with geological condition, and with those estimated by spectral inversion analysis are discussed.

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This paper discusses the validation of the probabilistic seismic hazard maps for Japan by comparing with the experienced seismic hazard maps developed from the earthquake catalog during the corresponding time period. Probabilistic and experienced seismic hazard maps for a time period of 30 years starting from 1890, 1920, 1950 and 1980 are developed. The probabilistic maps were consistent with the experienced maps in terms of the expected probabilities of exceeding various seismic intensities. Three regions due to the different characteristics of seismic hazard were also identified and mapped out. Appropriate risk management policies should be adopted according to the regional characteristics of seismic hazard.

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We developed earthquake damage estimation system considering building type using seismic intensity measure which had correlation with structural damage in order to estimate building and human damage more accurately. We estimated earthquake damage of past large earthquakes in Japan by the developed system. Comparing the results of earthquake damage estimation and actual damage data, we confirmed that proposed system is effective to estimate earthquake damage. We also confirmed that proposal system can estimate earthquake damage more accurately than earthquake damage estimation system using JMA Seismic Intensity.

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We developed a method of estimating 1-1.5sec. average response velocity which had correlation with structural damage, from JMA seismic intensity and PGA focused on JMA seismic intensity observation stations where strong ground motion records were lost. We showed that JMA seismic intensity and PGA has high correlation with 0-1.5 sec. and 0-1sec.average response velocity, respectively. Based on the result, we proposed the equation to estimate 1-1.5 sec. average response. Finally, we estimated 1-1.5 sec. average response of JMA seismic intensity observation stations where strong ground motion records were lost and confirmed that estimated 1-1.5 sec. average response has high correlation with structural damage.

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