2025-02-26 ミシガン大学
＜関連情報＞
- https://news.umich.edu/school-of-rock-properties-of-rocks-in-fault-zones-contribute-to-earthquake-generation/
- https://www.science.org/doi/10.1126/sciadv.adr9353
断層物質の不均質性がプレート間深部地震を制御する Fault material heterogeneity controls deep interplate earthquakes
Yihe Huang, Satoshi Ide, Aitaro Kato, Keisuke Yoshida, […], and Peng Zhai
Science Advances Published:26 Feb 2025
Abstract
Earthquakes may seem random, but are often concentrated in some localized areas. Thus, they are likely controlled by fault materials and stress heterogeneity, which are little understood. Here, we provide high-resolution observations of fault material and stress heterogeneity in the Japan subduction zone through an integration of material and source imaging with numerical simulations. Our results present evidence for localized, anisotropic structures with a near-zero Poisson’s ratio in the medium surrounding 1 to 2 kilometer–sized earthquake clusters, suggesting that the fault medium is damaged, foliated, and enriched with fluid. Such localized structures may cause stress perturbations on faults that in turn favor the frequent occurrence of deep interplate earthquakes at depths of 60 to 70 kilometers. Therefore, identifying the distribution and properties of fault material heterogeneity is important for more informed assessment of earthquake hazards.
