Re-analysis of broad-band magneto-telluric data in the focal region of the 2000 Western Tottori Earthquake

2000年鳥取県西部地震震源域の広帯域MTデータ再解析

中村 謙佑*; 相澤 広記*; 浅森 浩一; 大志万 直人*; 塩崎 一郎*; 2001年地殻比抵抗研究グループ*

Nakamura, Kensuke*; Aizawa, Koki*; Asamori, Koichi; Oshiman, Naoto*; Shiozaki, Ichiro*; The 2001 Research Group for Crustal Resistivity structure*

将来の地層処分システムに重大な影響を及ぼす可能性がある地震活動や火山活動の潜在的なリスクを適切に評価するためには、これらの自然現象と地殻内の流体やマグマといった不均質構造との関連性についての理解が必要である。本研究では、2000年鳥取県西部地震の震源域における詳細な比抵抗構造と断層すべり分布との関連性を検討するため、既往の研究に使用された広帯域電磁探査データに観測データをさらに加えて比抵抗構造解析を行った。

We show the resistivity structure around the focal region of the 2000 Western Tottori Earthquake (M7.3). The purpose of this study is to investigate the relationship between the rupture of the mainshock and the resistivity structure, which was not discussed in the previous study. By using the broad-band MT data, Umeda et al. (2011) imaged a deep conductive body in the middle crust to the upper mantle on the southwestern side of the mainshock rupture fault. However, they did not investigate the spatial relationship between the resistivity structure and the slip distribution. Therefore, in this re-analysis, we have spatial attention to the shape and uniqueness of the conductors. In addition to the previous broad-band MT data, we use broad-band MT data at 12 sites obtained by Universities (The 2001 Research Group for Crustal Resistivity structure, Japan, 2001). We use full components of the impedance tensor and geomagnetic transfer functions to image preliminary 3-D resistivity structure, and investigate its relationship to the slip distribution of the mainshock and also occurrence of the aftershocks.