中源地震活动性及其成因机制探讨  

Discussion on the seismicity and the seismogenic mechanism of intermediate-depth earthquakes

作　　者：徐志双 谭专条 王尅丰 章文波 XU Zhi-shuang;TAN Zhuan-tiao;WANG Kei-feng;ZHANG Wen-bo(China Earthquake Networks Center,Beijing 100045,China;Key Laboratory of Computational Geodynamics,College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国地震台网中心,北京100045 [2]中国科学院计算地球动力学重点实验室,中国科学院大学地球与行星科学学院,北京100049

出　　处：《地球物理学进展》2020年第4期1323-1331,共9页Progress in Geophysics

基　　金：中国地震局地震科技星火计划项目(XH20071Y)资助。

摘　　要：全球中源地震广泛分布于环太平洋地震带和地中海—喜马拉雅地震带,位于后者中段的兴都库什—帕米尔地震带是世界少有的位于大陆内部的中源地震聚集区.我国中源地震主要分布在东海—中国台湾岛—东沙群岛,以及新疆维吾尔自治区喀什—和田—阿克苏地区.2019年全球中源地震总频次较低,但M 7及以上强震数目略高于十年来平均水平.对于大洋俯冲带中源地震的成因,20世纪60年代以来,国内外学者进行了大量理论计算和实验研究工作,提出的主流观点包括:脱水脆化机制、热剪切失稳机制和黏滑机制.理论计算与地球物理观测、高温高压实验与野外证据等研究结果表明,俯冲带矿物脱水可以解释双地震带的成因,热剪切失稳和黏滑机制可以解释中源地震的反复性.事实上单独一种成因机制并不能完美解释中源地震的成因,可能不同区域的俯冲带地震由不同的成因机制占主导,其他机制也参与其中.Intermediate-depth earthquakes(classified with the depth from 70 to 300 km)widely distribute in the Pacific Rim earthquake zone and the Mediterranean-Himalayan earthquake zone.The Hindu Kush-Pamir earthquake zone,which is located at the mid part of the latter,is a rare intracontinent source of intermediate-depth earthquakes.In China,intermediate-depth earthquakes scatter mainly along East China Sea-Taiwan Island-Dongsha Islands,and Kashgar-Hotan-Aksu area in Xinjiang Uygur Autonomous Region.In 2019,the global intermediate-depth earthquakes showed low frequency,while the number of strong earthquakes with magnitude equal to or greater than M 7 was slightly higher than the average of the last ten years.Since the 1970 s,many theoretical calculations and experimental studies have been conducted by scholars around the world to study the seismogenic mechanism of intermediate-depth earthquakes.Three main points have been put forward,i.e.dehydration embrittlement mechanism,thermal shear instability mechanism and stick-slip mechanism.Theoretical calculations,geophysical observation,high-temperature and high-pressure experimental studies and field evidences have shown that dehydration of hydrous minerals in subduction zones can explain the cause of the double seismic zone,that is,earthquakes in the upper plane are thought to result from dehydration embrittlement from the dehydration of the oceanic crust,and earthquakes in the lower plane from dehydration of antigorite,while thermal shear instability and stick-slip mechanism might account for the repeatability of intermediate-depth earthquakes.Actually,a single seismogenic mechanism does not perfectly explain the cause of the intermediate-depth earthquakes.It is more acceptable that the earthquakes in subduciton zones of different regions are dominated by different seismogenetic mechanisms,and other mechanisms are also involved.

关 键 词：中源地震 地震活动性 脱水脆化 热剪切失稳 黏滑机制 

分 类 号：P315[天文地球—地震学]