Inland Earthquakes

Research on the generation process of intraplate earthquakes. It is well known that seismic activity in the intraplate region of southwest Japan becomes high before a great plate boundary thrust earthquake along the Nankai trough. In order to reduce disasters by these intraplate earthquakes, we conduct research to clarify the process by which intraplate earthquakes are generated, which is not well known at present, and develop new methods of forecasting the occurrence of intraplate earthquakes.

Major research topics are as follows:
1) Anelastic deformation in the upper crust.

2) Stress accumulation process on intraplate earthquake faults resulting from heterogeneities in the lower crust.

3) Development of sophisticated inversion methods to infer models from observed data.

Relationship between Vp/Vs ratio and hypocentral distribution in the Western Nagano prefecture region. Microearthquakes are concentrated in the region with low Vp/Vs ratio.
Point-source images obtained by the back-projection (BP), hybrid back-projection (HBP), and damped least-square solution. The image of the point source, put at the origin, cannot be well reproduced by the BP and HBP methods.

Faculty Members

  • Professor Yoshihisa IIO


  • Professor Katsuya YAMORI


  • Associate Professor Yukitoshi FUKAHATA