Depth distribution and recovery process of seismic velocity change by combined analysis of seismological data

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K17788
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Solid earth and planetary physics
• Research Institution: Tohoku University
• Principal Investigator: Takagi Ryota 東北大学, 理学研究科, 助教 (10735963)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 地震波干渉法 / 地震波速度変化 / 常時微動 / 2011年東北地方太平洋沖地震 / 2018年北海道胆振東部地震

Outline of Final Research Achievements

The seismic velocity structure inside the earth changes before and after large earthquakes due to strain changes caused by strong motions and fault slips. It is considered that the seismic wave velocity changed during the earthquakes gradually recovers to the original state after the earthquakes. In this study, I detected the seismic velocity change associated with the 2011 Tohoku-Oki earthquake and the seismic velocity change and the underground structural change associated with the 2018 Hokkaido Eastern Iburi earthquake, and suggested their depth distribution. In addition, I contributed to the advancement of subsurface structure monitoring through the elucidation of the observed seismic wave field.

Free Research Field

固体地球物理学

Academic Significance and Societal Importance of the Research Achievements

地震波速度は地球内部状態によって変化するため、地震波速度の時間変化を推定することで地球内部状態をモニタリングできる。本研究では大地震に伴う地震波速度変化とその回復過程についての理解を深めるとともに、地震波形データを用いた地震波速度変化推定手法の高度化の可能性を示した。地震波速度変化のメカニズムの解明、および、地震波形データを用いた地球内部状態のモニタリングに向けて、本研究により基礎的な情報を与えることができた。