Estimation of fault strength based on fine-scale seismic structure of fault zone

基于断层带精细地震结构的断层强度估算

• 批准号: 21740320
• 负责人: KATO Aitaro
• 金额: $ 3.08万
• 依托单位: The University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Young Scientists (B)
• 财政年份: 2009
• 资助国家: 日本
• 起止时间: 2009 至 2011
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-21740320/
• 关键词: 地震; 断層; 構造; 稠密アレイ観測; 余震; 断層破砕帯

We deployed a dense seismic array consisting of 120 portable stations, which crossed fault zones associated with the Iwate-Miyagi Nairiku Earthquake in 2008, and retrieved continuous seismic waveforms during about ten days. Based on tomographic analysis using the waveforms of small earthquakes located close to the array, we estimated a seismic structure of the fault zones. Bands of low-velocity layers were imaged roughly parallel to along pre-existing faults. We interpret that a likely-explanation of these low-velocity layers is presence of crustal fluids or cracks within the fault zones. It is thus inferred that the strength of fault might be weak.

我们部署了一个由120个便携式台站组成的密集地震台阵，这些台阵跨越了2008年岩手-宫城内陆地震的断层带，并在大约10天的时间里获得了连续的地震波形。基于层析成像分析，使用位于靠近阵列的小地震的波形，我们估计了断裂带的地震结构。低速层带大致平行于沿着预先存在的断层成像。我们认为，这些低速层的一个可能的解释是地壳流体或断裂带内的裂缝的存在。由此推断，断层的强度可能较弱。