ESR analytical method for simultaneously estimating the age and magnitude of paleoearthquakes from fault rocks

2015 Fiscal Year Final Research Report

• Project/Area Number: 25560175
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Natural disaster / Disaster prevention science
• Research Institution: University of Yamanashi
• Principal Investigator: FUKUCHI Tatsuro 山梨大学, 総合研究部, 教授 (90212183)
• Research Collaborator: IMAI Noboru 産業技術総合研究所, 地球科学情報研究部門, テクニカルスタッフ (20356512) ; TANAKA Mami 山梨大学, 教育人間科学部, 学部生 ; KITTA Takuto 山梨大学, 教育人間科学部, 学部生 ; INAMURA Hayato 山梨大学, 教育人間科学部, 学部生 ; TAGUCHI Daishi 山梨大学, 教育人間科学部, 学部生 ; HIROSE Takuya 山梨大学, 教育人間科学部, 学部生 ; IWASAKI Keita 山梨大学, 教育人間科学部, 学部生
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: 活断層 / 古地震 / 断層岩 / スメクタイト / 電子スピン共鳴 / ESR / ESR年代測定 / FMR

Outline of Final Research Achievements

I have carried out X-ray diffraction (XRD) analysis of fault rocks of the Itoigawa-Shizuoka Tectonic Line (ISTL) to estimate the age of fault movement of the ISTL. The XRD analysis shows that the existence of smectites becomes an index for the evaluation of fault activity. As a result of ESR dating of fault rocks of the ISTL, I confirm that ESR ages theoretically show the maximum age of the latest fault movement. The active zone of the ISTL is further extended to the 5km south of the present zone recognized as the ISTL Active Fault System. On the other hand, FMR signals, which is available in calculation of frictional heat energy necessary for the estimation of seismic magnitude, are not detected from the black fault rocks of the ISTL. The ESR spectral analysis of the Nojima fault rocks reveals that the source mineral of FMR signals is magnetite produced due to the disproportionation reaction progressing with thermal decomposition of siderite.

Free Research Field

構造地質学、地球年代学