2011年4月11日福島県浜通りの地震で引き起こされた地すべり・表層崩壊の分布特性

抄録

  Iwaki City in the southeast corner of Fukushima Prefecture in eastern Japan experienced an active-fault earthquake, named the Fukushima Hamadori earthquake (JMA magnitude 7.0), on April 11 in 2011. This earthquake was an “induced-earthquake” that occurred as a result of the Great Tohoku earthquake on March 11 in 2011. Two surface active faults appeared, and many landslides and surface slope failures were induced by the earthquake motion. We developed a landslide map to characterize the distribution of landslides using aerial and satellite images. This map shows that the landslides were relatively distributed around the hanging-wall side of the faults, which appear to be normal faults. The previous studies have shown that most of the landslides were caused by reverse fault type earthquakes, which were concentrated around the hanging-wall side and were under the influence of the “hanging-wall effect.” We think that the distribution of landslides caused by normal fault types during the time period under investigation was influenced by the “hanging-wall effect” similar to landslide distribution caused by reverse fault types.