Katsuhiro Kamae

• Kyoto University

We examined the scaling relationships of inland crustal earthquakes occurring in tectonically active regions such as the Japanese Islands. Two important points related to reliable scaling relationships are discussed empirically: the objective estimation of source parameters such as the seismic moment and rupture area, and the regionality of the sca...

We constructed a three-dimensional (3-D) subsurface structure model beneath the Wakayama Plain by combining the following three results: (1) the distributions of the depth of the sediment-bedrock interface and P-wave velocity in a sedimentary layer (referred to as Shoubudani Group) were estimated from the seismic reflection survey and the gravity p...

We evaluated the influence of nonlinear earthquake response by nonhomogeneous property value distribution model on spatially variation of seismic ground motions and foundation ground stability (minimum slip safety factor) based on numerical experiments, for ground near the building foundation. In order to make the ground that is as close to reality...

Simple evaluation of the degree of structural damage suffered by high-rise RC buildings after being subjected to strong ground motions is extremely important. For a large number of high-rise RC residential buildings for which strong-motion measurements or observations of microtremors before and after earthquakes have not been carried out, we develo...

A magnitude 6.6 of JMA scale earthquake occurred in central Tottori prefecture in Japan on 21 October 2016. The fault plane was estimated to be a high-angle left lateral fault with the strike of NNW–SSE direction from CMT solution and after-shock distribution. Strong ground motions were generated near source area and caused severe damage to many ho...

We evaluated the influence of the S-wave-velocity inhomogeneity of subsurface structure and the frequency and envelope features of input ground motions on the ground-motion spatially variations and the foundation-ground stability based on the numerical experiment using two-dimensional FEM model, considering ground nonlinearity. As a result, we foun...

A two-stage scaling relationship of the source parameters for crustal earthquakes in Japan has previously been constructed, in which source parameters obtained from the results of waveform inversion of strong motion data are combined with parameters estimated based on geological and geomorphological surveys. A three-stage scaling relationship was s...

This study used strong-motion records from the three-dimensional-dense-array observation network at the Hamaoka Nuclear Power Plant to evaluate the spatial variation (coherency and variation in Fourier amplitude ratio between points) of seismic motion in hard soil. The evaluated spatial variation characteristics of seismic motion were used to deriv...

For this study we used hierarchical heterogeneous source modeling procedure of Sekiguchi et al., 2008. This modelling approach is a result of compilation of many source observations (inversions) of strong earthquakes and allow easily generate possible variations of slip distributions. As a result, we can apply probabilistic approach to study genera...

We used simulation by the reciprocity method to visualize the distribution of Green’s function amplitudes in the source of a megathrust earthquake in the Nankai Trough and considered the effects of various areas (asperities or strong motion generation areas) on the simulated long-period ground motions at Konohana in the Osaka basin. We employed a f...

We evaluated spatial variations (i.e. lagged coherency and standard deviation of Fourier amplitude ratio between observation points) of seismic ground motions in hard soil, focusing on the difference of depth levels and horizontal and vertical components in addition to the frequency and the horizontal distance between the observation points, using...

Simple evaluation of the degrees of structural damage suffered by high-rise RC buildings after being subjected to long-period strong ground motions is extremely important to the development of life continuity planning for building residents. However, these evaluations cannot be based on seismic and microtremor records because these observation equi...

Using the waveform inversion results of recent eighteen crustal earthquakes (Mw5.4-6.9) in Japan, which happened after the 1995 Hyogo-ken Nanbu earthquake, we extracted the source parameters (entire rupture area (S) and asperity area (Sa)) from the inverted heterogeneous slip distributions following the criterion of Somerville et al.(1999). We reco...

Estimating the velocity structure of microseisms based on the horizontal-to-vertical spectral ratio (HVSR) is an extremely practical means of modelling the subsurface structure necessary for strong ground motion predictions. Thus, beyond the traditional framework of the 1-D velocity structure, the HVSR, derived from observation records of microseis...

For mitigating seismic damage of structures during disastrous earthquakes, we have to improve both the procedure for constructing source models for future earthquakes and the method for estimating strong ground motions. The empirical Green's function method (EGFM) is one of the most appropriate methods for estimating strong ground motions near sour...

The two microtremor features, namely, the H/V spectra and the dispersion curves, on the basin periphery area were investigated to the southern Osaka basin. In the coastal area with a gentle basement inclination, the S-wave velocity profile identified from the two features gave the appropriate basement depth. On the other hand, in the terrace area w...

We attempt to make the best-fit source models for simulating strong ground motions from the 2007 Niigata-ken Chuetsu-oki earthquake (Mw 6.6). We collected the source models obtained by the waveform inversion analysis and by the forward modeling using the strong motion data from the 2007 Chuetsu-oki earthquake. Observed records near source have thre...

There is a high possibility of reoccurrence of the Tonankai and Nankai earthquakes along the Nankai Trough in Japan. It is very important to predict the long-period ground motions from the next Tonankai and Nankai earthquakes with moment magnitudes of 8.1 and 8.4, respectively, to mitigate their disastrous effects. In this study, long-period (>2.5...

A preliminary source model composed of asperities for the 2005 off-shore Miyagi prefecture, Japan, earthquake (MJMA=7.2) was estimated by the empirical Green's function method. The source parameters for two asperities located on the fault plane were determined by comparing synthesized broad-band ground motions with observed ones at several stations...

Source modeling plays a key role in strong ground motion prediction for future large earthquakes. Recently, characterized source model composed of asperities introduced in Irikura's recipe is popularly used in broad- band strong ground motion prediction for scenario earthquakes in Japan. To advance the prediction, the validation of such modeling sh...

We propose an improved fault model of the Hyogo-ken Nanbu Earthquake for which an asperity is placed on the branch fault (branch fault model). The branch fault model is based on the result of source inversion which suggests that the rupture of the fault propagated also to the branch fault on the way. The result of the ground motion simulation by us...

There is high possibility of the occurrence of the Tonankai and Nankai earthquakes which are capable of causing immense damage. During these huge earthquakes, long period ground motions may strike mega-cities Osaka and Nagoya located inside the Osaka and Nobi basins in which there are many long period and low damping structures (such as tall buildi...

Strong ground motions are related with slip heterogeneity inside the source rather than the entire rupture area from the waveform inversion results of source rupture processes using strong motion data during large earthquakes. Such asperities are defined as regions that have two times slip as large as the average slip over the rupture area (Somervi...

A preliminary source model composed of asperities for the 2004 Mid Niigata Prefecture, Japan, earthquake (MJMA =6.8) was estimated by the empirical Green's function method. The source parameters for two asperities located on the fault plane were determined from the comparisons of the synthesized broad-band ground motions with the observed ones at s...

A preliminary source model composed of asperities for the 2003 Tokachi-oki, Japan, earthquake (MJMA = 8.0) was estimated by the empirical Green's function method. The source parameters for three asperities located on the fault plane were determined from the comparisons of the synthesized broad-band ground motions with the observed ones. We found th...

SUMMARY From recent development of the waveform inversion analyses for estimating rupture process using strong motion data during large earthquakes, we have understood that strong ground motion is relevant to slip heterogeneity inside the source rather than average slip in the entire rupture area. Asperities are characterized as regions that have l...

In Japan, the Central Disaster Prevention Council in Japan has opened the seismic intensity map due to future huge subduction earthquake linked by Nankai and Tonankai earthquakes occurred on the Nankai trough. In this study, we tried to predict broad-band strong ground motions of engineering interest during future subduction earthquakes using the e...

The hybrid technique combined theoretical calculation with stochastic one is powerful in predicting broad-band strong ground motions from future large earthquakes. Kamae et al. (1998) has demonstrated its powerfulness through some simulations of near-source strong ground motions in the 1995 Kobe earthquake, Japan. Then, in the stochastic calculatio...

From recent development of the waveform inversion analysis for estimating rupture process during large earthquakes, we have understood that strong ground motion is relevant to slip heterogeneity inside the source rather than the entire rupture area. The source characterization was made defining the entire rupture areas with a certain criterion in s...

We propose a recipe of predicting strong ground motions for future scenario earthquakes. It is made based on two kinds of scaling relationships, outer and inner fault parameters with respect to seismic moment. The outer fault parameters are defined as entire rupture area and total seismic moment. The total fault length is given as a sum of active f...

In Japan, long-term probabilities of several large subduction earthquakes have been evaluated by the Headquaters for Earthquake Research Promotion. In order to mitigate the disaster caused by such earthquakes, it is very important to predict broad-band strong ground motions of engineering interest before events. A methodology has been proposed for...

This study presents a 3D hybrid method for computation of 3D seismic motion inside basin. The hybrid method is based on the discrete wavenumber (DW) and fourth-order finite difference (FD) method. In the first step of the hybrid technique, DW method is used to calculate 3-component excitation on a finite difference grids surrounding 3D basin struct...

In the 2000 Tottori-ken Seibu earthquake, many strong ground motions of the main-shock and the aftershocks have been observed at a lot of stations including near-source area. In this study, we attempted to construct a source model for broad-band strong ground motions by the forward modeling using the empirical Green's function method. We derived th...

Most of the uncertainties in predicting strong ground motion is to model source heterogeneities of future earthquakes. An available method we propose for characterizing the heterogeneous slip distribution on the fault plane is based on the empirical source characterization derived from the slip models of the crustal earthquakes by Somerville et al....

We propose a recipe of predicting strong ground motions from an earthquake caused by specific active faults. From recent developments of the waveform inversion analysis for estimating rupture processes during large earthquakes, we have understood that strong ground motion is relevant to slip heterogeneity inside the source rather than the entire ru...

We simulate strong ground motions during the 1948 Fukui earthquake with the JMA magnitude 7.1 based on a heterogeneous source model and the hybrid simulation technique. So far there are no existing source models available for simulating strong ground motions from the 1948 Fukui earthquake. Most of the source models have been assumed to have uniform...

A method for simulating strong ground motion for a large earthquake based on synthetic Green's function is presented. We use the synthetic motions of a small event as Green' s functions instead of observed records of small events. Ground motions from small events are calculated using a hybrid scheme combining deter- ministic and stochastic approach...

The 1995 Hyogo-Ken Nanbu earthquake struck the heavily populated Kobe and adjacent cities in western Japan. More than 6400 people were killed, and more than 150,000 buildings were destroyed. The characteristics of mainshock ground motions in the heavily damaged area are needed to understand how buildings and bridges performed and why they reached f...

The 1995 Hyogo-Ken Nanbu earthquake struck the heavily populated Kobe and adjacent cities in western Japan. More than 6400 people were killed, and more than 150,000 buildings were destroyed. The characteristics of mainshock ground motions in the heavily damaged area are needed to understand how buildings and bridges performed and why they reached f...

This paper presents some tests on the empirical Green's function method, performed in order to check its effectiveness to predict strong ground motion during future large earthquakes. These investigations basically consist of blind or pseudo-blind tests using part of the data set obtained at the Volvi (Greece) test-site within the framework of the...

We introduce a generalized method for simulating strong ground motion from large earthquakes by summing subevent records to follow the ?2 law. The original idea of the method is based on a constant stress parameter between the target event and the subevent. It is applicable to a case where both events have a different stress drop after some manipul...

It is very important to predict strong ground motion in and around Osaka from great earthquakes recurrently occurring along the Nankai trough. In this paper, strong ground motions from the 1946 Nankai earthquake have been simulated at 11 sites including Osaka city by using the empirical Green's function method: We find that the source model with tw...

In order to predict more practically strong ground motion, it is important to study how to use a semi-empirical method in case of having no oppropriate observation records for actual small-events as empirical Green's functions. We propose a prediction procedure using artificially simulated small ground motions as substitute for the actual motions....

We propose a synthetic procedure for predicting strong ground motion at a specific site from a future large earthquake using a semi-empirical method. First, we estimate regional scaling relations of source parameters based on the earthquake observation in the objective region. Next we propose the operations to correct the empirical Green's function...

Prediction of strong ground motion at a site near a fault is an important subject for the earthquake resistant design of a structure such as a reactor building. In this paper, we apply the semi-empirical synthesis method by IRIKURA (1983, 1986) to the estimation of site specific ground motion using accelerograms observed at Kumatori in Osaka prefec...

The Nankai Trough earthquakes which are subduction earthquakes with magnitude greater than 8 have occurred at intervals of 90 to 150 years. The probability of earthquake occurrence within 30-years from January 1, 2008 are estimated at 60 -70% and 50 % for the next Tonankai and Nankai earthquakes, respectively, showing very high possibility of the e...

The Niigataken Chuetsu-oki earthquake (M j =6.8) occurred on July 16, 2007, northwest-off Kashiwazaki in Niigata prefecture, Japan. In this earthquake, severe damages of fifteen people dead, about 1319 collapsed houses and so on around Kashiwazaki have been caused. In particular, strong ground motions struck the Kashiwazaki and Kariwa nuclear power...

High-rise buildings in mega-cities such as Osaka and Nagoya in Japan have a high probability of damage due to strong long-period ground motions from a great subduction earthquake. We predict the damage potential of steel and reinforced concrete high-rise buildings and construct damage prediction maps for the Osaka basin using the long-period ground...