A Study on monitoring of seismic EM waves focusing on a low-frequency range below 10 Hz

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K05053
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 25030:Disaster prevention engineering-related
• Research Institution: Kanazawa Institute of Technology
• Principal Investigator: KAWAI JUN 金沢工業大学, 先端電子技術応用研究所, 教授 (10468978)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: SQUID / 電磁波 / 地震 / ピエゾ磁気効果 / シューマン共鳴 / 電離層アルフヴェン波共鳴

Outline of Final Research Achievements

We performed comparative observations of week natural electromagnetic signals including the geomagnetic field, focusing on seismic activities, using two highly sensitive SQUID magnetometer systems, in Hakusan City, Wajima City, and Suzu City. We confirmed that correlated signals because of the global electromagnetic phenomenon were detected at both sites, and local signals can be separated by comparing the data obtained at different site. When the M5.4 earthquake occurred in Suzu City on June 19, 2022, a sudden change in the signal was detected in the period from the rupturing time to the arrival time of the P-wave. We speculate that the piezomagnetic signal associated with the rupture of the fault was detected. Through this study, we think the SQUID magnetometer is available for monitoring electromagnetic signals associated with seismic activities.

Free Research Field

微小磁気計測

Academic Significance and Societal Importance of the Research Achievements

超高感度なSQUID磁力計を用いて、地震活動に伴う電磁信号の検出を目的に観測を行った。様々な信号が検出され、地震とは関係なく別の自然現象として同定されるものもあれば、不可解な信号も多く見られた。またM5.4の地震の際には断層破壊によって発生する信号が検出された。この現象は過去にM7.2の地震の震源直近でSQUIDよりも感度の低い磁力計で検出されていることが報告されているが、SQUID磁力計を用いれば、小さい規模の地震や、遠くで発生する地震の場合にも検出できることが期待される。地震波の到達前にこの信号が検出できることは、SQUID磁力計が防災や地震活動の研究において有効であると考えられる。