Features of landslides by the Kumamoto Earthquake, in April 2016, compared with the past landslides by rainfall events
Abstract
The Kumamoto Earthquake, a series of seismic activities having occurred since April 14, 2016 in Kumamoto, Japan, triggered a number of landslides that caused a severe disaster. The foreshock (21:26 on April 14, M6.5 (JMA)) and the main shock (1:25 on April 16, M7.3 (JMA)) were the major trigger-shakes. Most of landslides are thought to have occurred by the main shake. In this research, we aim at clarifying the features of the landslides occurred in the Kumamoto earthquake. The results are compared with those of the past landslides occurred by rainfall events in the surrounding areas. The landslides by the Kumamoto Earthquake are distributed widely in the Aso caldera and its surrounding area, while the landslides that caused economic and/or human damages are mainly found in the center of the western Aso caldera. This area is located in the destructive domain of eastern edge of the Fudagawa Fault that caused the earthquake, and therefore received the stronger shake. The wall of the Aso caldera consisted of lava and welded pyroclastic rocks, while the inside area of Aso caldera is mainly constituted by Kuroboku soil and volcanic ashes. Slip slides were also clearly formed at some landslides inside the Aso caldera. Depth of the landslides was typically about 1-2 m, but deeper depth of about 10 m was also observed. There were many landslides which flowed a long distance. Most landslides had the tendency to be mostly distributed on ridge or a plane slope. A heavy rainfall event occurred in the northeast part of Aso caldera in 2012 triggered many shallow landslides of less than 1m deep, distributed in valleys. These features are major difference between the landslides by the earthquake and by the rainfall and provide an important aspect to improve prevention of landslide disaster.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFMNH43C1877D
- Keywords:
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- 4326 Exposure;
- NATURAL HAZARDSDE: 4328 Risk;
- NATURAL HAZARDSDE: 4330 Vulnerability;
- NATURAL HAZARDSDE: 4337 Remote sensing and disasters;
- NATURAL HAZARDS