Is the diversity of fault slip defined by structural heterogeneity?

2022 Fiscal Year Final Research Report

• Project/Area Number: 19H01992
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 17040:Solid earth sciences-related
• Research Institution: Kyoto University
• Principal Investigator: Yoshimura Ryokei 京都大学, 防災研究所, 教授 (50346061)
• Co-Investigator(Kenkyū-buntansha): 小川 康雄 東京工業大学, 理学院, 教授 (10334525) ; MORI JamesJiro 京都大学, 防災研究所, 教授 (50314282) ; 高田 陽一郎 北海道大学, 理学研究院, 准教授 (80466458)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 比抵抗構造 / 不均質 / 断層クリープ運動 / 固着域

Outline of Final Research Achievements

In this study, we conducted observational studies on a plate boundary fault (Bolu-Gerede segment, North Anatolian Fault Zone, Turkey) and an inland active fault (Atotsugawa Fault, Japan), where slip diversity is observed, to determine whether heterogeneity in the electrical resistivity structure is found in the subsurface corresponding to the diversity, and if so, whether it is common. The purpose of this observational study is to clarify whether heterogeneity in the subsurface electrical resistivity structure is observed in response to the diversity of the fault segments. We obtained broadband MT data at 44 sites around the Atotsugawa Fault and 36 sites around the North Anatolian Fault Zone. Along the Atotsugawa Fault, heterogeneity of resistivity structures corresponding to differences in seismic activity and surface displacement velocity fields was observed.

Free Research Field

地球内部電磁気学

Academic Significance and Societal Importance of the Research Achievements

過去に大地震が発生し、また、その周辺でクリープ的地表変動が観測されている断層を対象に、そのようなすべりの多様性が地下構造の不均質性によって規定されているかを明らかにするために、3次元解析に資する面的なデータを取得したことは非常に意義深い。また、地下構造の不均質性に共通性が認められれば、固着域を地震発生前に評価できる可能性があり、社会的な意義も大きい。