Rapid deployment of a seismic network to record the aftershocks of the Mw=6.2 Aisen earthquake in Southern Chile

最大的地震(例如智利，1960年；安达曼-苏门答腊岛，2004年)发生在会聚的板块边界，那里的海洋板块俯冲到其他构造板块的下方。在板块汇聚期间，巨大的应力积聚，导致大地震。了解应力分布将促进我们对地震发生的了解，并可能导致更好地预测未来俯冲带特定区段的最大可能震级。然而，对盖覆板中的耦合力和应力分布仍然缺乏详细的了解，特别是在斜向俯冲的情况下，预计会发生大范围的扭压变形。精确的地震位置和断层面解为解决这一问题提供了重要的约束条件。2007年4月21日发生在智利南部的S 45.4级地震为研究其在理想的自然实验室中的应力分布提供了独特的可能性。最近(2004/2005年)，几个时间上的地震台网研究了智利南部边缘的不同部分，其中还包括了1960年智利地震的破裂区域(Rietbrock等人，2004年；Haberland等人，2006年；Lange等人，2007年)。然而，由于爱森地区地震活动较低，这一1960年地震破裂结束的重要地段至今无法研究。利用目前的余震活动，这是可以纠正的；在可预见的未来，这可能是进行此类研究的唯一机会。

The largest earthquakes (e.g. Chile, 1960; Andaman-Sumatra, 2004) are generated at convergent plate boundaries, where oceanic plates subduct beneath other tectonic plates. During plate convergent, large stresses build up causing major earthquakes. Understanding the stress distribution would foster our knowledge of earthquake occurrence and might lead to better prediction of maximum possible magnitudes in the future at given segments of a subduction zone. However, a detailed knowledge of the coupling forces and the stress distribution in the overriding plate is still lacking, especially in the case of oblique subduction in which bulk transpressional deformation is expected. Precise earthquake locations together with fault plane solutions provide important constraints to solve this problem. The Aisen Southern Chile earthquake at 45.4 S on April 21, 2007 gives a unique possibility to study the stress distribution since it occurred in an ideal natural laboratory. Different segments of the Southern Chilean margin have been studied recently (2004/2005) by several temporal seismic networks also incorporating the rupture area of the 1960 Chile earthquake (Rietbrock et al, 2004; Haberland et al., 2006; Lange et al., 2007). However, due to the low seismicity of the Aisen region, this important segment, where the rupture of the 1960 earthquake ended, could not be studied so far. Using the current aftershock activity this can be rectified; it may be the only chance for such a study in the foreseeable future.