Author(s)

TARA NIDHI LOHANI, TAKASHI NAGAO & YASUHIRO FUKUSHIMA

Abstract

The 2016 Kumamoto Earthquake has caused vast building damages and human losses, although Japan is one of the world’s well-prepared countries against earthquake disaster. The accelerometers set in Mashiki town area of Kumamoto prefecture rolled to the full scale measuring the seismic intensity as 7 in JMA scale of 7. In addition to such large shaking, there are opinions about the existence of three parallel fault lines beneath the town and the area lying on very soft volcanic soils regarding the vast damage of this particular area. In order to investigate the soil behaviour of this area, microtremor array studies were conducted starting from April 2016 to September 2016. Phase velocity obtained by spatial autocorrelation method was cross-checked with the borehole data available and was also found to be correlating well. Besides, the shear wave velocity distribution in the field was also consistent with the extent of damage observed after the earthquake.

Keywords

Earthquake, Kumamoto, Mashiki, microtremor, shear wave velocity.