Earthquake and tsunami forecasts: Relation of slow slip events to subsequent earthquake rupture
Earthquake and tsunami forecasts: Relation of slow slip events to subsequent earthquake rupture
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DOI：
10.1073/pnas.1412299111
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发表时间：
2014-12-02
影响因子：
11.1
通讯作者：
Gonzalez, Victor
中科院分区：
文献类型：
--
作者：
Dixon, Timothy H.;Jiang, Yan;Gonzalez, Victor
2012年9月5日发生在哥斯达黎加俯冲板块边界上的M-w 7.6地震遵循62年的地震间隔期。高精度GPS记录了地震前十年内的许多慢滑动事件（SSE），包括地震破裂的上倾和下倾。较深的SSE大于较浅的SSE，如果是震间周期的特征，则释放大部分锁定的地震下倾，限制下倾破裂和地震震级。较浅的SSE较小，解释了部分但不是全部的震间锁定。一次SSE发生在地震前几个月，但莫尔-库仑破坏应力的变化可能太小，不足以引发地震。由于许多SSE发生时没有后续破裂，它们的单独预测价值有限，但它们在地震前释放了大量累积的震间应变，有效地确定了后续地震破裂的区域（破裂没有发生在缓慢滑动常见的地方）。由于地震震级取决于破裂面积，这对地震危险性评估具有重要意义。具体来说，如果这种行为是未来地震周期和其他俯冲带的代表，这意味着监测SSE，包括位于海上的浅向上倾斜事件，可以导致准确的地震震级和海啸潜力的预测。
The 5 September 2012 M-w 7.6 earthquake on the Costa Rica subduction plate boundary followed a 62-y interseismic period. High-precision GPS recorded numerous slow slip events (SSEs) in the decade leading up to the earthquake, both up-dip and down-dip of seismic rupture. Deeper SSEs were larger than shallower ones and, if characteristic of the interseismic period, release most locking down-dip of the earthquake, limiting down-dip rupture and earthquake magnitude. Shallower SSEs were smaller, accounting for some but not all interseismic locking. One SSE occurred several months before the earthquake, but changes in Mohr-Coulomb failure stress were probably too small to trigger the earthquake. Because many SSEs have occurred without subsequent rupture, their individual predictive value is limited, but taken together they released a significant amount of accumulated interseismic strain before the earthquake, effectively defining the area of subsequent seismic rupture (rupture did not occur where slow slip was common). Because earthquake magnitude depends on rupture area, this has important implications for earthquake hazard assessment. Specifically, if this behavior is representative of future earthquake cycles and other subduction zones, it implies that monitoring SSEs, including shallow up-dip events that lie offshore, could lead to accurate forecasts of earthquake magnitude and tsunami potential.