Professor Shinji Toda, an expert on active faults in IRIDeS, calculated stress changes (changes in deformation before and after earthquakes) in the surrounding regions and faults after the magnitude 6.5 and 7.3 earthquakes, to find out the mechanism behind aftershocks which have been striking a wide area since April 16. In the figures below, stress is increasing in areas that are marked red, meaning fault activity may be induced, while regions marked in blue are places where stress is decreasing...

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In this field survey, it became clear that from the magnitude 7.3 earthquake on April 16, surface earthquake faults were identified along part of the Futagawa fault zone and in the northern part of the Hinagu fault zone, emerging on the surface. During the survey, a maximum of approximately two meters right-lateral strike-slip in the Futagawa fault zone was measured, while in the northern section of the Hinagu fault zone, a maximum of approximately 50 centimeter right-lateral strike-slip wa...

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During the emergency field survey of the International Research Institute of Disaster Science, Tohoku University, on April 17, the research team identified an area where a surface earthquake fault has appeared within the Hinagu fault zone, with a right-lateral strike-slip of approximately 25 centimeters in Takigawa, Mifune Town, Kamimashiki-gun, Kumamoto Prefecture. It seems that this rupture emerged at the magnitude 7.3 earthquake in predawn on April 16 (according to the landowner). Also, there...

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Professor Osamu Murao, Associate Professor Shuji Moriguchi and Associate Professor Akihiro Shibayama investigated the affected area in Kumamoto. Findings are summarized as follows: ・Most serious damages were found on old buildings and relatively small damages on new buildings ・Extensive damages were observed along the faults; especially heavy damages on houses with roof tiles ・It is necessary for key buildings such as city halls to have anti-seismic re-enforcement, to function as ...

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Assistant Professor Xin Wang of the Hazard and Risk Evaluation Research Division in IRIDeS, calculated damage and collapse ratios of wooden houses according to different building ages, and has pointed out there is a high possibility that old wooden houses may collapsed the most in the Kumamoto Earthquake. And it is necessary to consider the risk of old wooden houses for disaster prevention in future earthquakes. Assistant Professor Xin Wang calculated the damage and collapse ratios of woode...

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