Silica/clay diagenesis and its effect on interplate seismicity in subduction zones

2014 Fiscal Year Final Research Report

• Project/Area Number: 24740339
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Geology
• Research Institution: Hokkaido University (2013-2014); The University of Tokyo (2012)
• Principal Investigator: KAMEDA Jun 北海道大学, 理学(系)研究科(研究院), 准教授 (40568713)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: 東北地方太平洋沖地震 / スメクタイト / 続成作用

Outline of Final Research Achievements

The very large slip on the shallow portion of the subduction interface during the 2011 Tohoku-oki earthquake (Mw 9.0) caused a huge tsunami along the northeast coast of Honshu, Japan. In order to elucidate the mechanics of such tsunamigenic slip, mineralogical propery of the source fault rock was examined by using XRD. The analysis reveal that the fault zone that caused the earthquake is significantly enriched in smectite compared to the surrounding sediments, which may be intimately linked to the tsunamigenic shallow faulting.
The smectite-rich deposits are broadly distributed in the northwestern Pacific Ocean, and may therefore potentially enhance conditions for large shallow slip during earthquakes that occur over a broad area of the Japan Trench plate boundary, which would result in large tsunamis for this region.

Free Research Field

粘土鉱物学