Stress transfer relations among the earthquakes that occurred in Kerman province, southern Iran since 1981
Stress transfer relations among the earthquakes that occurred in Kerman province, southern Iran since 1981
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DOI：
10.1111/j.1365-246x.2006.03119.x
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发表时间：
2006-10
影响因子：
2.8
通讯作者：
S. Nalbant;S. Steacy;J. McCloskey
中科院分区：
文献类型：
--
作者：
S. Nalbant;S. Steacy;J. McCloskey
摘要我们探讨了1981年以来在伊朗南部克尔曼省发生的M≥6.4级地震可能的应力触发关系。计算了震后上地壳突然同震运动和下地壳和/或上地幔随时间变化的粘性松弛引起的应力变化。1981年至2005年间发生的4次M-≥6.4级地震，在郭克断裂及其附近均表现出明显的库仑应力载荷-破坏关系。然而，2003年巴姆6.5级地震发生在最近的Gowk地震西南约95公里处，与之前的地震显示出非常弱的应力关系。巴姆地震震中的同震静应力变化相当小(∼0.006巴)。根据粘弹性地壳模型的选择和有效摩擦系数的不同，震后应力随时间的变化可能是单独同震静应力的26倍或7倍。考虑到粘弹性地球模型中的不确定性和有效摩擦系数，我们不能自信地得出结论，2003年的Bam事件是通过同震或震后应力加载而更接近于破坏。有趣的是，与巴姆断层走向相似的高克南部地区，在1981至2003年间经历了高达8.3巴的应力负荷，至今尚未发生破坏性地震。
SUMMARY We explore the possible stress triggering relationship of the M ≥ 6.4 earthquakes that occurred in Kerman Province, southern Iran since 1981. We calculated stress changes due to both coseismic sudden movement in the upper crust and the time-dependent viscous relaxation of the lower crust and/or upper mantle following the event. Four events of M ≥ 6.4 occurred between 1981 and 2005, on and close to the Gowk fault, show a clear Coulomb stress load to failure relationship. The 2003 M = 6.5 Bam earthquake, however, which occurred approximately 95 km SW of the closest Gowk event, shows a very weak stress relation to preceding earthquakes. The coseismic static stress change at the hypocentre of the Bam earthquake is quite small (∼0.006 bars). The time-dependent post-seismic stress change could be 26 times larger or 7 times lower than that of coseismic static stress alone depending on the choice of viscoelastic crustal model and the effective coefficient of friction. Given the uncertainties in the viscoelastic earth models and the effective coefficient of friction, we cannot confidently conclude that the 2003 Bam event was brought closer to failure through coseismic or post-seismic stress loading. Interestingly, the southern Gowk segment with a similar strike to that of the Bam fault, experienced a stress load of up to 8.3 bars between 1981 and 2003, and is yet to have a damaging earthquake.