Rupture‐Depth‐Varying Seismicity Patterns for Major and Great (Mw ≥ 7.0) Megathrust Earthquakes
Rupture‐Depth‐Varying Seismicity Patterns for Major and Great (Mw ≥ 7.0) Megathrust Earthquakes
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DOI：
10.1002/2017gl074573
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发表时间：
2017-10
影响因子：
5.2
通讯作者：
N. Wetzler;T. Lay;E. Brodsky;H. Kanamori
中科院分区：
文献类型：
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作者：
N. Wetzler;T. Lay;E. Brodsky;H. Kanamori
俯冲带板块边界巨型逆冲上的大地震是应变积累和释放间隔的结果。中等规模余震的机制多样性和空间分布受主震破裂深度的影响。与局限于大逆冲断层较深部分的断裂事件相比，穿越浅层大逆冲断层至海沟附近的主震具有更大的板内余震断层多样性。随着主震的规模接近造成该地区大逆冲断层破裂的最大规模事件，板内余震断层的多样性也在增加。基于这些趋势，我们将“突破”破裂定义为那些涉及大型逆冲断层的浅层破裂，在板块边界周围具有体积广泛的弹性应变下降，允许受长期环境变形应力影响的多种板内断裂的激活。相比之下，余震断层机制的均匀性表明，弹性应变能的部分释放和另一次大破裂的可能性仍然存在。
Large earthquakes on subduction zone plate boundary megathrusts result from intervals of strain accumulation and release. The mechanism diversity and spatial distribution of moderate‐size aftershocks is influenced by the mainshock rupture depth extent. Mainshocks that rupture across the shallow megathrust to near the trench have greater intraplate aftershock faulting diversity than events with rupture confined to deeper portions of the megathrust. Diversity of intraplate aftershock faulting also increases as the size of the mainshock approaches the largest size event to have ruptured that region of the megathrust. Based on these tendencies, we identify “breakthrough” ruptures as those involving shallow rupture of the megathrust with volumetrically extensive elastic strain drop around the plate boundary that allows activation of diverse intraplate faulting influenced by long‐term ambient deformation stresses. In contrast, homogeneity of the aftershock faulting mechanisms indicates only partial release of elastic strain energy and remaining potential for another large rupture.