Propagation dynamics of seismic and aseismic slip governed by fault heterogeneity and Newtonian rheology
Propagation dynamics of seismic and aseismic slip governed by fault heterogeneity and Newtonian rheology
复制标题
DOI：
10.1029/2012jb009532
复制
发表时间：
2012-11-29
影响因子：
3.9
通讯作者：
Yamashita, Teruo
中科院分区：
文献类型：
--
作者：
Ando, Ryosuke;Takeda, Naoto;Yamashita, Teruo
称为阵发性震颤和滑动 (ETS) 事件的慢地震以低平均速度（类似于每天 10 公里）沿着几个伴随地震和地震滑动的板块界面传播超过 100 公里。这些低传播速度将慢地震与普通地震区分开来，因此了解其传播过程对于理解控制地震多样性和普遍性的弱约束物理学至关重要。我们基于将迁移模式与日本西南部板块边界断层上的震颤能量相关联的综合建模和观测，表明断层上的流变异质性主要控制 ETS 传播。该断层具有持续的小规模分段，其中ETS事件在相对脆性部分开始大力传播，并在相对韧性部分以抛物线模式普遍减速。基于这些抛物线震颤迁移模式的模拟自发破裂限制了牛顿塑性流的延展性或可能的膨胀强化，但拒绝大规模流体流动。我们讨论牛顿流变学背后可能的基本过程。该模型也与 2011 年 M-w 9.0 Tohoku-oki 地震之前观测到的地震活动迁移模式一致，表明 M-w 7.3 前震延迟触发。
Slow earthquakes called episodic tremor and slip (ETS) events propagate over 100 km at low average velocities, similar to 10 km per day, along several plate interfaces accompanying seismic and aseismic slip. These low propagation velocities differentiate slow earthquakes from ordinary earthquakes, and thus understanding their propagation processes is fundamental to understanding the poorly constrained physics governing the diversity and universality of earthquakes. We show that rheological heterogeneity on faults primarily governs ETS propagation on the basis of comprehensive modeling and observations that correlate migration patterns with the energetics of tremor on a plate-bounding fault in southwest Japan. The fault has persistent small-scale segmentation, in which ETS events started propagating energetically in relatively brittle sections and decelerated generally with a parabolic pattern in relatively ductile sections. Simulated spontaneous ruptures that are based on these parabolic tremor migration patterns constrain the cause of ductility to Newtonian plastic flow or perhaps dilatant strengthening, but reject large-scale fluid flows. We discuss possible elementary processes underlying the Newtonian rheology. This model is also consistent with the observed seismicity migration pattern before the 2011 M-w 9.0 Tohoku-oki earthquake, suggesting delayed triggering by the M-w 7.3 foreshock.