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2010年2月27日马乌莱(智利)M8.8地震使安第斯大逆冲型俯冲带的一部分区段破裂,该区段被认为具有极高的潜在地震危险性[1-6]。此次地震是使俯冲带内一个长期地震空区发生破裂的一次最大地震,在此之前,一个密集型空间大地测量台网对该俯冲带进行了监测。这就为评估震间闭锁与同震滑移的空间相关性提供了板块界面震前闭锁状态的前所未有的高分辨率图像。鉴于闭锁类似于滑动的基本假设,震前闭锁可被用于预测许多地震空区的未来破裂[6-12]。然而,没有第一次“填补空白”的地震的发生,这一假说就无法得以验证。在此,我们提供的证据表明,2010年马乌莱地震滑移分布状况与根据之前10年间全球定位系统(GPS)观测结果反演得到的震间闭锁分布密切相关。此次地震成核于一个闭锁程度很高的区域内,并将1835年大地震以来该区聚集的应力几乎释放一空。地震滑动量很大的两个区域(凸起体)在此次地震之前几乎处于完全闭锁状态。在这两个凸起体之间,此次破裂形成了一个处于震间蠕动状态的桥梁地带,其同震滑动量一贯较小。破裂中止于震前处于高度闭锁状态的区域,但其预应力却因20世纪重复发生的地震事件而大大降低。我们的结果显示,单个凸起体尺度内同震滑移的不均匀性应该能够说明未来大地震的潜在危险,由此,可以根据大地测量结果对其进行预测。
February 27, 2010 The M8.8 earthquake in Maule (Chile) ruptured a section of the Andean thrust belt that is considered to have a very high potential seismic hazard [1-6]. The earthquake was the single largest earthquake that ruptured a long-term seismic zone in the subduction zone, where an intensive geodetic survey network monitored the subduction zone. This provides an unprecedented high-resolution image of the interblock pre-earthquake blocking state for assessing the spatial correlation between the earthquakes and the coseismic slip. Pre-quake closure can be used to predict future fractures in many seismic areas, given the basic assumption that the blockade resembles sliding [6-12]. However, the hypothesis can not be validated without the first “fill-in-blank” earthquake. Here, we provide evidence that the distribution of the Maule earthquake in 2010 is closely related to the distribution of the inter-seismics lock-up distribution based on the results of the Global Positioning System (GPS) observations of the past 10 years. The earthquake was nucleated in a highly closed area and the stresses accumulated in the area were almost exhausted after the 1835 earthquake. The two areas with great earthquake slip (bump) were almost completely closed before the earthquake. Between the two convex bodies, the rupture formed a bridge zone in peristalsis of the epicenter, and the co-seismic slippage was consistently small. Bursting ended in a highly latched area prior to the earthquake, but its prestress was greatly reduced by repeated earthquakes in the 20th century. Our results show that the inhomogeneity of co-seismic slip within a single convex body scale should be able to account for the potential danger of future large earthquakes, from which they can be predicted based on geodetic measurements.