Mechanisms and detectability of seismically induced variations in the electromagnetic field

2021 Fiscal Year Final Research Report

• Project/Area Number: 17K05634
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Solid earth and planetary physics
• Research Institution: Kyoto University
• Principal Investigator: Yamazaki Ken'ichi 京都大学, 防災研究所, 助教 (20436588)
• Co-Investigator(Kenkyū-buntansha): 吉村 令慧 京都大学, 防災研究所, 教授 (50346061)
• Project Period (FY): 2017-04-01 – 2022-03-31
• Keywords: 地震 / 地磁気 / 地電位 / 時間変化 / 電気伝導度 / 界面導電現象 / 電磁誘導 / 地震時電磁場変動

Outline of Final Research Achievements

Temporal variations in the electromagnetic (EM) field in association with earthquakes have been observed for several earthquakes. However, their generation mechanisms have not been identified quantitatively although some candidate mechanisms have been proposed. The condition(s) of occurring such phenomena have also poorly been understood.
In the present study, we have established a calculation scheme through which we can predict temporal variations in the EM field in association with earthquakes in a variety of situations. Also, we have installed some observation sites at which the EM field are continuously recorded, and successfully catch some EM signals in association with earthquakes, which will be analyzed to reveal underling mechanisms of the observed phenomena in the near future.

Free Research Field

地球電磁気学

Academic Significance and Societal Importance of the Research Achievements

地震が起きるとき、地表付近で電磁場の変動がこれまでに観測されている。しかし、この現象がなぜ生じるのか、どんなタイミングでどんな地震に対してどんな場所で生じるのかは明らかではなかった。本研究の成果として、この問題を解明する上での基礎となる計算方法が確立されるとともに、新たな観測によって地震時電磁場変動の事例が積み上げられた。電磁場変動は地震動よりも早く伝搬するという特性があるため、これ等の成果を応用することで、現在実用化されている緊急地震速報をさらに早く出せるようになるかもしれない。