GIS and Geoinformation Zoning for Disaster Mitigation (GIZ2018)
Effect of the subsoil condition on the seismic response at Mashiki Town by the 2016 Kumamoto Earthquake
2019 年 6 巻 2 号 p. 30-37
詳細
2019 年 6 巻 2 号 p. 30-37
Serious disaster took place in Mashiki Town of Kumamoto Prefecture, Japan by the 2016 Kumamoto Earthquakes. The authors carried out boring investigation together with undisturbed sampling of soils at the two different sites. One is located in the area where there is almost no damage, and another is in the seriously destructed area. In the present paper, a series of one-dimensional seismic assessments in terms of the total stress numerical analysis is conducted for the above-mentioned two locations. The calculated performance shows that the response acceleration at the ground surface at the seriously damaged site reaches 1200gal due to amplification in the sand/clay alternating strata near the surface while the maximum acceleration at the base exhibits 250gal with the predominant period of 0.9s. On the other hand, remarkable attenuation is found to occur in the middle of the thick soft clay layer at the no damaged site, which results in the relatively smaller response acceleration, 700gal at the ground surface. The difference in this ground vibration between both sites is investigated by comparing the transfer functions calculated for the individual sites. Then, it is found that the mode of ground vibration is strongly dependent upon the interactive relation between the characteristics of the earthquake wave and the subsoil condition.
