夏垫断裂带地震地下流体的同震响应研究

地震地下流体已成为一种重要的地震监测手段。 本文分析夏垫断裂带上观测井的同震响应特征, 探讨观测井水位、 水温同震变化对夏垫断裂带的影响机理, 收集和整理布设在夏垫断裂带上的赵各庄井和西集井两口观测井水位和水温同震响应资料, 从响应的地震次数及发震位置、 异常幅度、 时间和形态类型等方面对其响应特征进行分析, 从震中距、 震级和井-含水层岩性等方面探讨了地下流体地震前兆异常的成因。 结果显示, 赵各庄井和西集井水位地震响应能力强于水温, 响应形态以振荡型为主, 对于M_S7.0以上地震具有显著的映震能力。 在水温资料中, 仅有赵各庄井对2008年汶川M_S8.0地震有响应, 响应幅度为0.0129℃。 综合分析认为, 井-含水层岩性影响了两井同震响应形态特征, 远场大地震产生的动态应变导致了较大的水位变幅。

Study on the Coseismic Response of Seismic Underground Fluid in Xiadian Fault Zone

Subsurface fluids observation has already become an important mean for monitoring earthquake. Therefore, this paper assembled and summarized typical coseismic response data of underground water level and temperature collected from wells on the Xiadian fault, for analyzing underground fluids coseismic response characteristics and impact. This work studies response characteristics of fluid data such as responsive seismic frequency, anomaly range, time, types of behaviors, and gives some discussions on epicentral distance, earthquake magnitude and well-aquifer lithology for anomaly genesis. The analysis results show that the response capacity of groundwater level data is more prominent then that of water temperature collected from well Zhaogezhuang and Xiji, and that response behaviors give priority to the oscillation type which has striking response to ≥M_S7.0 earthquake, moreover, indicate that water temperature data only respond to Wenchuan M_S8.0 earthquake which are collected from well Zhaogezhuang with response amplitude 0.0129℃. Comprehensive analysis suggests that well-aquifer lithology affects coseismic responsive behaviors and characteristics of the two wells, and that the dynamic strain generated by large far-field earthquake result in large fluctuation of groundwater level.