2015年智利Illapel M_W8.3地震同震效应及其对南美大陆地震危险性影响

The co-seismic effect of the 2015 Chile Illapel M_W8.3 earthquake and its effect on seismic risk of South America

基于高性能并行有限元方法,建立含地表地形和Moho面起伏的大规模非均匀椭球地球模型,计算了2015年9月17日智利Illapel M_W8.3地震同震效应,同时讨论2010年智利Maule M_W8.8地震和2014年智利Iquique M_W8.1地震对2015年智利Illapel地震的加载作用,进一步分析这3个地震共同作用对南美大陆及周围断层的地震危险性影响.结果表明:对此次智利Illapel地震CEA(中国地震局地球物理研究所)滑动模型计算的地表最大水平位移约为3 m,USGS(美国地调局)模型的最大水平位移约6 m.特大地震影响范围广,南美大陆接近一半区域同震水平位移量级达到0.5 mm;受3次地震共同作用,智利2010年Maule地震南部俯冲带、2015年Illapel地震和2014年Iquique地震之间俯冲带,以及2014年Iquique地震以北俯冲带,受到10 kPa东西向压应力加载;2010年Maule地震和2014年Iquique地震共同加速了2015年Illapel地震滑动;1960年Valdivia M_W9.5地震破裂区、2014年Iquique地震和1995年Antofagasta地震之间区域以及2010年Maule地震和2015年Illapel地震的未破裂区重合处库仑应力变化均超过10 kPa,有可能加速强震的发生.

In this paper, based on the parallel finite element method, the large-scale non-uniform ellipsoidal earth model including topography and Moho discontinuity is constructed to investigate the co-seismic effect of the 2015 Illapel, Chile Mw8.3 earthquake. Then, the Coulomb stress changes associated with 2010 Maule Mw8. 8 earthquake and 2014 Iquique Mw8.1 earthquake are superposed on the fault of the 2015 Illapel Mw8.3 earthquake, and the combined effect on seismic risk of South America induced by these three events is discussed. The USGS slip model predicts the maximum displacement around 6 m, while the predicted displacement from the CEA slip model is up to 3 m. Horizontal displacement in nearly half of South American territory is in the magnitude order of 0.5 mm. The subduction zones on the south of 2010 Maule earthquake, between the 2014 Iquique earthquake and 2015 Illapel earthquake, and on the north of the 2014 earthquake are under a stress loading of 10 kPa. The 2010 Maule and 2014 Iquique earthquakes has accelerated the slip of the 2015 Illapel earthquake. The Coulomb stress changes in the rupture zone of the 1960 Valdivia earthquake, the fault 1995 Antofagasta earthquake, and the overlap of zone between the 2014 Iquique earthquake and all exceed 10 kPa, which may hasten the occurrence of strong earthquakes.