Derode Benoit, Madariaga Raúl, Campos Jaime
Department of Geophysics (DGF), University of Chile, Blanco Encalada 2002, Santiago, Chile.
Laboratoire de Géologie, PSL University, Ecole Normale Supérieure et CNRS, 75230, Paris, France.
Sci Rep. 2021 Feb 1;11(1):2705. doi: 10.1038/s41598-021-82152-0.
The M 8.8 Maule earthquake is the largest well-recorded megathrust earthquake reported in South America. It is known to have had very few foreshocks due to its locking degree, and a strong aftershock activity. We analyze seismic activity in the area of the 27 February 2010, M 8.8 Maule earthquake at different time scales from 2000 to 2019. We differentiate the seismicity located inside the coseismic rupture zone of the main shock from that located in the areas surrounding the rupture zone. Using an original spatial and temporal method of seismic comparison, we find that after a period of seismic activity, the rupture zone at the plate interface experienced a long-term seismic quiescence before the main shock. Furthermore, a few days before the main shock, a set of seismic bursts of foreshocks located within the highest coseismic displacement area is observed. We show that after the main shock, the seismic rate decelerates during a period of 3 years, until reaching its initial interseismic value. We conclude that this megathrust earthquake is the consequence of various preparation stages increasing the locking degree at the plate interface and following an irregular pattern of seismic activity at large and short time scales.
8.8级马乌莱地震是南美洲有详细记录以来最大的逆冲型地震。由于其闭锁程度，已知此次地震的前震极少，且余震活动强烈。我们分析了2000年至2019年不同时间尺度下2010年2月27日发生的8.8级马乌莱地震区域的地震活动。我们将主震同震破裂区内的地震活动与破裂区周围区域的地震活动区分开来。通过一种独特的时空地震对比方法，我们发现，在一段地震活动期之后，板块界面处的破裂区在主震发生前经历了长期的地震平静期。此外，在主震发生前几天，在同震位移最大的区域内观测到了一组前震地震群。我们表明，主震之后，地震活动率在3年时间内逐渐减缓，直至恢复到初始的震间值。我们得出结论，这次逆冲型地震是不同准备阶段的结果，这些阶段增加了板块界面处的闭锁程度，并且在大时间尺度和小时间尺度上都呈现出不规则的地震活动模式。
