Importance of small earthquakes for stress transfers and earthquake triggering
Importance of small earthquakes for stress transfers and earthquake triggering
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DOI：
10.1029/2004jb003286
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发表时间：
2004-07
影响因子：
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通讯作者：
A. Helmstetter;A. Helmstetter;Y. Kagan;D. Jackson
中科院分区：
文献类型：
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作者：
A. Helmstetter;A. Helmstetter;Y. Kagan;D. Jackson
[1]我们估计了小地震和大地震对于静应力变化和地震触发的相对重要性，假设地震是由静应力变化触发的，并且地震位于d维的分形网络上。该模型预测，m级地震触发的事件数量和该地震在其他地震位置引起的应力变化都随着m的增加而增加，类似于10（Dm/2）。空间聚类越强，小地震对未来事件发生地应力变化和地震触发的影响越大。如果地震震级遵循古腾堡-里希特定律，b / b / D/2，小地震集体主导应力传递和地震触发，因为它们的高频率克服了它们较小的单个触发潜力。使用南加州的目录，我们观察到m级地震引发的地震活动率随着m为10（alpha m）而增加，其中alpha = 1.05 +/- 0.05。我们还发现，触发地震的震级分布与触发地震的震级m无关。当alpha接近b时，小地震对地震触发的重要性与大地震大致相同。我们使用两个重新定位的目录来评估南加州震源的分形相关维数D。距离0.1 < r < 5 km时测量到的D值对于Shearer等人的星表为D = 1.54，对于Hauksson等人的星表为D = 1.73。D值既反映了断层网的结构，也反映了地震相互作用的性质。通过只考虑那些间隔时间大于1000天的地震对，我们可以在很大程度上消除短期聚类的影响。那么D近似于2，接近假设地震触发是由静力引起的预测值D = 2 alpha = 2.1。D值接近2b意味着小地震与大地震对于地震间的应力传递同样重要，考虑小地震引起的应力变化应该改进地震相互作用的模型。
[1] We estimate the relative importance of small and large earthquakes for static stress changes and for earthquake triggering, assuming that earthquakes are triggered by static stress changes and that earthquakes are located on a fractal network of dimension D. This model predicts that both the number of events triggered by an earthquake of magnitude m and the stress change induced by this earthquake at the location of other earthquakes increase with m as similar to 10(Dm/2). The stronger the spatial clustering, the larger the influence of small earthquakes on stress changes at the location of a future event as well as earthquake triggering. If earthquake magnitudes follow the Gutenberg-Richter law with b > D/2, small earthquakes collectively dominate stress transfer and earthquake triggering because their greater frequency overcomes their smaller individual triggering potential. Using a southern California catalog, we observe that the rate of seismicity triggered by an earthquake of magnitude m increases with m as 10(alpha m), where alpha = 1.05 +/- 0.05. We also find that the magnitude distribution of triggered earthquakes is independent of the triggering earthquake's magnitude m. When alpha approximate to b, small earthquakes are roughly as important to earthquake triggering as larger ones. We evaluate the fractal correlation dimension D of hypocenters using two relocated catalogs for southern California. The value of D measured for distances 0.1 < r < 5 km is D = 1.54 for the Shearer et al. catalog and D = 1.73 for the Hauksson et al. catalog. The value of D reflects both the structure of the fault network and the nature of earthquake interactions. By considering only those earthquake pairs with interevent times larger than 1000 days, we can largely remove the effects of short-term clustering. Then D approximate to 2, close to the value D = 2 alpha = 2.1 predicted by assuming that earthquake triggering is due to static stress. The value D approximate to 2b implies that small earthquakes are as important as larger ones for stress transfers between earthquakes and that considering stress changes induced by small earthquakes should improve models of earthquake interactions.