Modeling of stress transfer in the Coquimbo region of central Chile
Modeling of stress transfer in the Coquimbo region of central Chile
复制标题
智利中部科金博地区的应力传递建模
DOI：
10.1029/2004jb003440
复制
发表时间：
2006
影响因子：
--
通讯作者：
J. Campos
中科院分区：
文献类型：
--
作者：
A. Gardi;A. Lemoine;R. Madariaga;J. Campos
[1]我们研究了智利中部科金博地区的地震活动性和应力转移，自1997年7月以来，该地区发生了一系列超过12次震级从6到7.6的地震。在这一地区，海洋纳斯卡板块俯冲到南美洲大陆岩石圈之下。在50 km以下，下行板块相对于南美板块以接近6.5 cm/年的速率抗震滑动。科金博地区是1880年和1943年发生8级以上大地震的地点。经过多年的平静，板块交界面的地震活动在1997年中期突然增加，并至少持续到2004年。第一组事件发生在1997年7月锁定接骨板界面中部。1997年10月，地震活动向内陆转移到Punitaqui-Ovalle地区，正好位于从孕震区向地震滑动区过渡的上方。该系列的主要事件是M = 7.6 1997年10月15日Punitaqui地震。这是一个发生在60公里深度的实验室内压缩地震，位于非常接近孕震耦合界面下倾边缘的近垂直平面上。我们模拟了孕震区底部附近地震的库仑应力传递。我们发现，一个简单的模型，从深度大于50公里的地震滑动应力转移可以解释触发不仅Punitaqui地震，但也是1997年7月序列。额外的模拟表明，1997年事件之后近7年的地震活动也可以简单地解释为1997年事件和地震滑动导致的孕震板块界面库仑应力增加的结果。
[1] We study the seismicity and stress transfer in the Coquimbo region of central Chile, where an exceptional series of more than 12 earthquakes of magnitudes from 6 to 7.6 has occurred since July 1997. In this area, the oceanic Nazca plate is subducted under the continental lithosphere of South America. Below 50 km, the downgoing slab slips aseismically with respect to the South American plate at a rate close to 6.5 cm/yr. The Coquimbo region was the site of major earthquakes of M > 8 in 1880 and 1943. After many years of quiescence, the seismic activity of the plate interface suddenly increased in mid-1997 and continued at least until 2004. The first group of events occurred in July 1997 in the middle of the locked plate interface. In October 1997, the activity moved inland to the Punitaqui-Ovalle area, just above the transition from the seismogenic zone to that of aseismic slip. The main event of the series was the M = 7.6 15 October 1997 Punitaqui earthquake. This is an intraslab compressional earthquake that occurred at $60 km depth, on a subvertical plane located very close to the downdip edge of the seismogenic coupled interface. We performed simulations of Coulomb stress transfer for earthquakes near the bottom of the seismogenic zone. We found that a simple model of stress transfer from the aseismic slip at depths greater than 50 km can explain the triggering not only of the Punitaqui earthquake but also of the July 1997 sequence. Additional simulations show that the seismicity that followed the 1997 event for almost 7 years can also be simply explained as a result of increased Coulomb stresses on the seismogenic plate interface as a result of the 1997 event and aseismic slip.