Subduction Zone Paleoearthquake Research Group

Recent paleoseismological research unveiled that subduction zone earthquake unusually becomes greater due to multi-segment rupture of seismic sources such as the 2011 great Tohoku Earthquake. To predict such earthquake, it is important to reveal the rupture history of past several thousand years. We survey traces of past earthquake and tsunami recorded in coastal topography and sediments to evaluate recurrence time and magnitude. From geophysical interpretation of the field data combining with present instrumental observation data, we provide useful information to disaster mitigation.

Comparison of tsunami inundation areas between the 869 Joagn earthquake and the 2011 great Tohoku earthquake.

Comparison of tsunami inundation areas between the 869 Joagn earthquake and the 2011 great Tohoku earthquake. Base map is 1/50,000 [Ishinomaki] and [Matsushima] published by Geospatial Information Authority of Japan. Tsunami inundation of the 869 Jogan earthquake is based on model 10 in Sawai et al. (2012).

 

Drifted boulders around Hashigui-iwa in Kushimoto, Wakayama Prefecture.

Drifted boulders around Hashigui-iwa in Kushimoto, Wakayama Prefecture. The boulders were probably transported by large tsunami associated with great earthquake along the Nankai Trough.