Inferring earthquake rupture direction from curved slickenlines

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K22368
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund
• Review Section: 0204:Astronomy, earth and planetary science, and related fields
• Research Institution: Kyoto University
• Principal Investigator: Kaneko Yoshihiro 京都大学, 理学研究科, 准教授 (10880255)
• Project Period (FY): 2020-09-11 – 2023-03-31
• Keywords: 破壊伝播方向 / 断層条線 / 大地震 / 動的破壊シミュレーション

Outline of Final Research Achievements

Currently, we are unable to understand the details of earthquakes that occurred in the distant past. In this work, we propose a new method to uncover the rupture propagation direction of past large earthquakes using geological features preserved on faults scarps, called slickenlines. Slickenlines are scratch marks that form when two sides of a fault move past one another during an earthquake. We developed a theoretical framework that links the geometry of slickenlines with rupture propagation direction for all types of faults and test our model using a global catalog of surface-breaking earthquakes. Our results reveal a strong link between our model and the available data, providing a new way to uncover the rupture direction of large earthquakes that are not recorded by modern seismic instruments.

Free Research Field

地震発生物理学

Academic Significance and Societal Importance of the Research Achievements

本研究の結果により、地震時に断層面上で記録される条線の湾曲の向きと断層の破壊伝播方向との間に関係性があり、条線の観察から古地震の破壊伝播方向を推定できる可能性が示された。本研究で得られた知見は、世界で起きた古地震の破壊伝播方向の推定や地震ハザードの理解の向上に繋がるものと期待される。