Potential of large slip at the shallow portion of plate-boundary fault: Effect of dehydration of clay minerals

2017 Fiscal Year Final Research Report

• Project/Area Number: 15H03737
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Geology
• Research Institution: Osaka University
• Principal Investigator: Hirono Tetsuro 大阪大学, 理学研究科, 准教授 (70371713)
• Co-Investigator(Renkei-kenkyūsha): SHIBAZAKI Bunichiro 独立行政法人建築研究所, 国際地震工学センター, 上席研究員 (20344012) ; TSUDA Kenichi 清水建設株式会社, 技術研究所・原子力技術センター, 研究員 (60470324) ; TANIKAWA Wataru 独立行政法人海洋研究開発機構, 高知コア研究所, 研究員 (70435840)
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: 南海地震

Outline of Final Research Achievements

Near-trench slip during large earthquakes is an important factor in the generation of destructive tsunamis. The amplitude of the slip is related not only to stress drop and dynamic mechanisms but also to properties of the fault rocks. Here, we constrain the near-trench slip potential of the plate-boundary fault of the Japan Trench and the megasplay fault of the Nankai Trough by integrating laboratory-derived properties of actual fault samples and dynamic rupture simulations. The Nankai Trough fault materials are sandy and have higher permeability and porosity than the clayey materials of the Japan Trench. However, dynamic weakening by thermal pressurization is greater at the Nankai Trough, because of the higher friction and higher interstitial fluid content. Dynamic earthquake rupture simulations reproduced the large slip near the trench observed in the 2011 Tohoku-oki earthquake and suggest that a Nankai Trough earthquake has a strong potential to produce a much larger slip.

Free Research Field

地震断層学