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Prevention of Large Earthquakes beneath Big Cities

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Title: Prevention of Large Earthquakes beneath Big Cities
Authors: Fujii, Yoshiaki Browse this author →KAKEN DB
Kodama, Jun-ichi Browse this author →KAKEN DB
Fukuda, Daisuke Browse this author →KAKEN DB
Keywords: Large earthquakes beneath big cities
Induced seismicity
Silica carbide compositen
Water injectio
Issue Date: 26-Sep-2017
Publisher: 資源・素材学会
Journal Title: MMIJ Fall Meeting 2017
Volume: 4
Issue: 2
Start Page: 3305-12-02
Abstract: Twenty two M ≥ 6 earthquakes occurred beneath big cities between 2000 and 2016, for example, in Japan excluding aftershocks. They induced severe human and property damages. By Kumamoto 2016 (M6.5), for example, 110 people died, 184,643 buildings including the Kumamoto Castle collapsed and the economic loss was 2.4-4.6 trillion JPY. Gradual release of seismic energy by injecting water through a drill hole to the seismic fault is proposed. An M6 is occurring at the average interval of 100 years in Kumamoto for example. One thousand M4 earthquakes (an M4 causes almost no damage in Kumamoto) in 100 years will release the seismic energy for an M6. Namely, 10 M4 for one year or ca. an M4 for a month will prevent an M6 earthquake. The necessary water amount is 9.4 x 105 m3 for an injection based on a study on mostly cases of enhanced geothermal system (EGS). The scheduled injections would be carried out very carefully under a dense microseismic and seismic monitoring to ensure safety. Focal depths of typical large earthquakes under big cities are deeper than the deepest records of drilling. The problems of deep drilling are high temperature and corrosion and would be solved by the silica carbide composite and electro pulse drilling. The total cost of ca. 56 billion JPY is much cheaper than the economic damage. The risk of unexpected induction of an M6 can be minimized by gradual injection under careful monitoring. The injection can be cancelled when the released energy exceeds an M4.
Description: MMIJ Fall Meeting 2017, Sept. 26-28 2017, Sapporo, Japan (資源・素材2017(札幌): 平成29年度資源・素材関係学協会合同秋季大会, 2017年9月26日~28日, 北海道大学, 札幌市)
Conference Name: MMIJ Fall Meeting
資源・素材2017(札幌): 平成29年度資源・素材関係学協会合同秋季大会
Conference Place: Sapporo
Type: proceedings
Appears in Collections:工学院・工学研究院 (Graduate School of Engineering / Faculty of Engineering) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 藤井 義明

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