Japan Geoscience Union Meeting 2016

Presentation information


Symbol M (Multidisciplinary and Interdisciplinary) » M-IS Intersection

[M-IS34] The 2016 Kumamoto Earthquake and related crustal activities

Wed. May 25, 2016 5:15 PM - 6:30 PM Poster Hall (International Exhibition Hall HALL6)

5:15 PM - 6:30 PM

[MIS34-P20] Three-dimensional seismic velocity structure in Kyushu including the source region of the 2016 Kumamoto earthquake

*Azusa Shito1, Satoshi Matsumoto1, Hiroshi Shimizu1, Group for urgent joint seismic observation of the 2016 Kumamoto earthquake (1.Institute of Seismology and Volcanology, Kyushu University)

Keywords:The 2016 Kumamoto earthquake

The 2016 Kumamoto earthquake is a series of earthquakes, including an earthquake with magnitude of Mj=7.3 which occurred on April 16, 2016 beneath Kumamoto City, the preceding earthquake with magnitude of Mj=6.5 which occurred on April 14, 2016, and many triggered aftershocks. The two main earthquakes were located along the Futagawa and Hinagu fault zones in the west area of Beppu-Shimabara graben.

The purpose of the study is to reveal detailed crustal structures and its tectonic process of the successive large earthquakes generation. We estimated three-dimensional seismic wave velocities in the crust beneath Kyushu including the source region of the Kumamoto earthquakes by applying double-difference tomography method [Zhang and Thurber, 2003]. The local earthquake data (from January 2000 to July 2013, m > 2, depth < 30 km) were collected by the Institute of Seismology and Volcanology (SEVO), Kyushu University. For the tomographic inversion, we used 159,103 P-wave and 115,265 S-wave arrival times from 4,126 local earthquakes. The initial velocity model is the same as the one used for routine earthquake location processing in SEVO, Kyushu University.

We will discuss the relation between the 2016 Kumamoto earthquakes and the tectonic background inferred from the seismic wave velocity structure.

This work is partly supported by JSPS KAKENHI Grant Number JP15J40067, MEXT KAKENHI Grant Number 16H06298, MEXT under its Earthquake and Volcano Hazards Observation and Research Program, and Earthquake Research Institute, The University of Tokyo under Joint Usage Program. We thank Dr. Okada and Dr. Nakajima for their constructive comments.