Rupture Process of The 2011 Tohoku-Oki Earthquake: Analysis by using Green's Tensor Waveforms

2014 Fiscal Year Final Research Report

• Project/Area Number: 24540452
• 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: Tokyo Institute of Technology
• Principal Investigator: OKAMOTO Taro 東京工業大学, 理工学研究科, 助教 (40270920)
• Co-Investigator(Kenkyū-buntansha): TAKENAKA Hiroshi 岡山大学, 自然科学研究科, 教授 (30253397)
• Co-Investigator(Renkei-kenkyūsha): SUGIOKA Hiroko 海洋研究開発機構, 地球深部ダイナミクス研究分野, 主任研究員 (00359184)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: 東北地方太平洋沖地震 / 破壊過程 / ３次元構造 / 差分法 / GPU計算 / 波形インバージョン

Outline of Final Research Achievements

We analyzed "seismic" rupture process of the March 11, 2011 Tohoku-Oki earthquake (GCMT Mw9.1) by using a non-linear multi-time-window waveform inversion analysis. We used Green's tensor waveforms computed for laterally heterogeneous structure models: full 3D model was used for strong-motion Green's tensor waveforms, and 2.5D structure models were used for teleseismic P-wave Green's functions. The inferred slip distribution was characterized by large slips near the hypocenter with maximum slip of about 37 m. The near-trench slips were inferred to be relatively small. An isolated slip region was also identified at deep beneath the coast of Fukushima prefecture. On the other hand, large amount of "artificial" slips were inferred close to the trench when we apply 1D Green's functions that did not incorporate the effect of realistic lateral heterogeneity. Our result suggests the trench-ward large deformation that caused large tsunamis did not radiated strong seismic waves.

Free Research Field

固体地球惑星物理学