稳定的爬行断层段可能会由于动态减弱而变得具有破坏性
1Institute for Research on Earth Evolution, Japan Agency for Marine-Earth Science and Technology, Yokohama, Kanagawa, 236-0001, Japan. hnoda@jamstec.go.jp
Nature
|January 11, 2013
概括
地震断层可以表现出缓慢的爬行和突然的破裂,挑战以前的假设. 一个新的模型解释了剪切加热如何在爬行断层段上允许不稳定的滑动,从而影响地震危险评估.
科学领域:
- 地质物理学 地质物理学
- 构造学 构造学 构造学 构造学
- 地震学 地震学
背景情况:
- 地球地的断层通过缓慢的滑动或快速的,产生地震的破裂来适应构造板块运动.
- 断段通常根据摩擦类型进行分类:速度增强 (稳定滑动) 或速度减弱 (粘滑动).
- 2011年东北奥基地震在一个被认为是爬行区的大滑坡挑战了这些假设.
研究的目的:
- 提出一个模型,整合稳定的爬行和co-seismic减弱的故障行为.
- 解释通常爬行的段落上如何发生不稳定的滑动.
- 复制和解释来自东北奥基和奇奇地震的复杂观测结果.
主要方法:
- 开发了一种模型,将低滑速的增速摩擦与通过孔液剪切加热的协震减弱相结合.
- 为了模型参数化,利用了1999年奇奇地震断层区域的实验室测量结果.
- 采用了一种新的数值方法,结合所有波浪效应来模拟长期滑动行为.
主要成果:
- 该模型成功地重现了对故障行为的看似矛盾的观察.
- 它解释了来自低滑坡区域的高频辐射和爬行部分的大滑坡.
- 该模型解释了东北奥基断裂的复杂性和历史地震性模式.
结论:
- 地震破裂可以通过以前被认为是障碍物的爬行断层传播.
- 这一发现需要重新评估许多地区的地震危险评估.
- 拟议的模型为各种故障滑动行为提供了统一的解释.
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