地质力学学报2018，Vol.24Issue(3)：309-320,12.DOI:10.12090/j.issn.1006-6616.2018.24.03.033
大地震前后实测地应力状态变化及其意义——以龙门山断裂带为例
EVALUATING MEASURED IN-SITU STRESS STATE CHANGES ASSOCIATED WITH EARTHQUAKES AND ITS IMPLICATIONS: A CASE STUDY IN THE LONGMENSHAN FAULT ZONE
摘要
Abstract
Evaluating measured in-situ stress state changes associated with large earthquake events plays a crucial role in earthquake prediction using measured in-situ stress data, whereas typical examples were not stated systematically yet.In this study, the Qiaoqi and Yingxiu regions which contain measured in-situ stress data crossing two large earthquakes ( the Wenchuan earthquake and the Lushan earthquake) were selected as examples to study this issue.The changes of the stress state before and after the Wenchuan and Lushan earthquakes in the Qiaoqi and Yingxiu regions were analyzed by comparing the magnitudes of gradient coefficient, characteristic indexes KHV( ratio of the maximum horizontal stress to vertical stress), KHh( ratio of the maximum horizontal stress to minimum horizontal stress), and μm (shear stress normalized by average stress) obtained before and after these two earthquakes.The results indicate that the average magnitudes of KHV, KHh, and μmobtained after the Lushan earthquake (QQ-14) in Qiaoqi region are larger than those obtained before the Wenchuan earthquake (QQ-99); and the mean magnitudes of these parameters obtained from QQ-99 are larger than those obtained after the Wenchuan earthquake (QQ-09).However, the evolution feature of gradient coefficient before and after these two earthquakes can be characterized by QQ-09＞QQ-14＞QQ-99.Based on above estimation, it was stated that the changes of KHV, KHh, μmcan reflect the evolution trend of the regional tectonic stress filed in Qiaoqi region, while the gradient coefficient can not reflect the evolution feature accurately enough.The magnitudes of gradient coefficient, KHV, and μmobtained from measured in-situ stress data after the Wenchuan earthquake exceed those after this large earthquake in Yingxiu region, while the KHhshows contradictory trend.The tectonic stress evolution in Yingxiu region should be verified by supplementing additional stress data.Long-term measured in-situ stress data which can be compared is the key element in significant breakthrough of earthquake prediction using the change laws of stress state characteristics parameters.Conclusions drawn in this study is of great significance for tectonic stress field estimation and disaster prevention and reduction in Longmenshan region, and can provide reference for earthquake prediction research.关键词
地应力/地震/特征参数/龙门山断裂带/地震预报Key words
in-situ stress/earthquake/characteristic parameter/the Longmenshan fault zone/earthquake prediction分类
天文与地球科学引用本文复制引用
秦向辉,陈群策,孟文,谭成轩,张重远,丰成君..大地震前后实测地应力状态变化及其意义——以龙门山断裂带为例[J].地质力学学报,2018,24(3):309-320,12.基金项目
国家自然科学基金项目(41702351) （41702351）
国家科技重大专项(2016ZX05034-003) （2016ZX05034-003）
中国地质调查局项目(121201104000150003) （121201104000150003）
