MMIJ & EARTH 2017, Sapporo

Presentation information (2017/08/24 Ver.)

General Session

Rock Engineering

Thu. Sep 28, 2017 1:00 PM - 3:15 PM B31 (Fl.1.,Build. B3)

Chairman: Takahiro Funatsu (Kyushu university), Yoshiaki Fujii (Hokkaido university)

1:15 PM - 1:30 PM

[3305-12-02] Prevention of Large Earthquakes beneath Big Cities

○Yoshiaki Fujii1, Jun-ichi Kodama1, Daisuke Fukuda1 (1. Hokkaido University)

Chairman: Takahiro Funatsu (Kyushu university)

Keywords:Large earthquakes beneath big cities, Prevention, Induced seismicity, Silica carbide composite, Water injection

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.

講演PDFファイルダウンロードパスワード認証

講演集に収録された講演PDFファイルのダウンロードにはパスワードが必要です。

現在有効なパスワードは、[資源・素材学会会員専用パスワード]です。
※[資源・素材学会会員専用パスワード]は【会員マイページ】にてご確認ください。(毎年1月に変更いたします。)

[資源・素材学会会員専用パスワード]を入力してください

Password