Determination of focal mechanisms of non-volcanic tremors based on their wavefield properties and elucidation of generation mechanisms of tremors

2014 Fiscal Year Final Research Report

• Project/Area Number: 24540463
• 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: National Institute of Advanced Industrial Science and Technology
• Principal Investigator: IMANISHI Kazutoshi 独立行政法人産業技術総合研究所, 活断層・火山研究部門, 研究グループ長 (70356517)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: 非火山性深部低周波微動 / 振動特性 / メカニズム解 / 臨時地震観測 / 西南日本

Outline of Final Research Achievements

We proposed a method to determine focal mechanisms of non-volcanic tremors using S-wave polarization data. Because the shear-wave splitting analysis indicated the need of the correction for splitting effects, we also developed a procedure to recover the source S-wave polarization angle. We applied the present method to a tremor sequence at Kii Peninsula, southwest Japan and confirmed its applicability. Most estimated focal mechanism solutions show low-angle thrust faults, which are basically consistent with the geometry of the plate interface. We also found some events that contain strike-slip components at a specific location, providing us an important tool for inferring detailed stress fields around the plate boundary as well as the geometry of plate interface.

Free Research Field

地震学