Seismicity modulated by stress changes below 1kPa: From global to local scales

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K04036
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 17040:Solid earth sciences-related
• Research Institution: Shizuoka University
• Principal Investigator: Mitsui Yuta 静岡大学, 理学部, 准教授 (80717950)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 地震 / GNSS / 余効変動 / スローイベント / 沈み込み帯 / 摩擦 / 深発地震 / 機械学習

Outline of Final Research Achievements

In this research project, we developed fundamental techniques for analyses of surface displacement data and conducted comparative studies of surface displacement and seismicity. The two main results are as follows: (1) We found that there was a difference in the temporal decay of the postseismic deformation and the aftershock activity of the 2011 off the Pacific coast of Tohoku earthquake. By modeling both of them following the power law, we showed that their characteristics were different from the results predicted from simple friction dynamics. (2) At the Tonga Trench subduction zone, we found that surface transient displacement and quiescence of deep earthquake seismicity occurred at about the same time, suggesting that a large-scale slow event may have occurred.

Free Research Field

固体地球物理学

Academic Significance and Societal Importance of the Research Achievements

本研究では、地下の地震活動と地表で観測される変位との関係について、機械学習など情報科学分野の技術を取り入れつつ、解析を進めた。その結果、大きな地震の後に余震がどのように減っていくか、あるいは、プレート沈み込み帯の浅部と深部にどのような繋がりがあり得るかに関して、複数の知見を得た。いずれも、複雑な時空間的性質を持つ地震活動の定量的理解を深める上で、1つのカギとなるものである。