南美西海岸(智利)地震科学研究回顾及其对地震监测预报的启示

智利俯冲带是全球地震活动最为活跃的地区之一,2010年以来已经发生了3次8级强震。本文在调研了该地区地震地质、历史地震、运动学特征等方面研究成果的基础上,梳理了其中与地震预测预报有关的观测现象,总结了相关科学问题的研究进展和认识过程。结果显示:(1)智利俯冲带历史地震记录丰富,基于现代大地测量的断层震间闭锁研究深入,近年来多次8级地震均发生在历史地震破裂空段和滑动亏损较大的强闭锁区;(2) 2010年Maule M_W8.8地震和2014年Iquique M_W8.1地震震前均有不同程度的前兆变化,Maule M_W8.8地震前主要是"一类空区"和"二类空区"的嵌套;而Iquique M_W8.1地震前还伴有b值持续降低,前震活动频繁,GPS时间序列瞬态变化等一系列短临异常变化;(3)同震位错和震间闭锁的空间分布显示智利俯冲带断层摩擦性质复杂;(4)孕震物理力学机制复杂,不同学者不同方法之间还存在一些认识争议。

Earthquake Science on the Western Coast of South American (Chile)and Implications for Earthquake Prediction: An Overview

The Chilean subduction is one of the highest seismic activity zone in the world, which has been attacked by three large earthquake of M_W>8 since 2010. Based on related studies on seismic geology, historical earthquake, kinematic characterizes, etc., some interesting phenomenon that related to earthquake prediction and the relative research and cognition progress are summarized in this paper. ① Due to the well recorded historic earthquake and the comprehensive research on modern geodesy data-based interseismic fault locking, seismic gap and the high slip deficit locking zone have dominated several large earthquake in the recent years. ② Some seismogenic related precursors are found before the 2010 Maule M_W8.8 and the 2014 Iquique M_W8.1 earthquake. Different with the nesting of the two kinds of Mogi seismic gap before 2010 Maule M_W8.8 earthquake, continuously decreasing of b-value, clustering of pre-shocks, suddenly changes of GPS transient signal, etc., were sprung up before the main shock of the 2014 Iquique M_W8.1 earthquake. ③ The spatial distribution of coseismic slip and interseismic locking reveals the diversity of fault frictional properties. ④ Many cognitional debate on seismogenic physical mechanism and its complexity are still ongoing between different scientists and different methods. ⑤ After the combination of literature investigation and our daily work,some preliminary understanding and thinking are also discussed in this paper.