Estimation of S-wave velocity model around Kanto basin by using MeSO-net

2020 Fiscal Year Final Research Report

• Project/Area Number: 19K23544
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund
• Review Section: 0303:Civil engineering, social systems engineering, safety engineering, disaster prevention engineering, and related fields
• Research Institution: National Institute of Advanced Industrial Science and Technology
• Principal Investigator: Nimiya Hiro 国立研究開発法人産業技術総合研究所, 地質調査総合センター, 研究員 (40849923)
• Project Period (FY): 2019-08-30 – 2021-03-31
• Keywords: 地震波干渉法 / S波速度構造 / 表面波トモグラフィ / 地震波

Outline of Final Research Achievements

We estimated the subsurface S-wave velocity structure in and around the Tokyo metropolitan area by using the surface-wave phase velocities. Surface waves were extracted from weak vibrations which we cannot feel (ambient noise) by using the dense seismic observation network installed mainly in the Tokyo metropolitan area. In this study, the effect of surface wave attenuation was reduced by focusing on a specific frequency, and the surface wave velocity at a high frequency which can reflect the detailed subsurface structure was estimated. In order to improve the accuracy of the estimation of the subsurface velocity structure, Rayleigh and Love waves were extracted from the vertical and horizontal component of the vibration, respectively. The velocity structure of the subsurface S-wave was estimated by inverse analysis using the phase velocity of each wave.

Free Research Field

物理探査

Academic Significance and Societal Importance of the Research Achievements

地震発生時に大きな被害が予想される首都圏において，地震波の伝播を知るうえで重要なS波速度構造を精度よく推定することは，地震防災のために急務である．本研究では、首都圏地震観測網(MeSO-net)で観測された雑微動データを用いて，地震計間を伝播する表面波（レイリー波とラブ波）を合成し，その伝播速度から首都圏およびその周辺の3次元S波速度構造を推定した．また，表面波伝播速度を精度よく推定することは，3次元S波速度構造の高精度化のために重要である．