利用位于华蓥山断裂带的重庆荣昌井水温数字化分钟值观测资料,统计分析了该井水温对2008年1月—2021年9月全球M_S≥7.0、川滇地区M_S≥6.0、重庆及周边地区M_S≥4.0共273次地震的同震-震后响应动态特征,对井水温同震优势方向成因和机理进行了深入研究,获得以下认识:①荣昌井水温同震-震后响应能力较好,对近震和远震均可记录到;该井水温同震响应由深及浅的顺序发生,响应持续时间随观测深度的增加而增加,响应幅度随观测深度的增加而减小,且该井水温同震-震后响应持续时间较同井水位的长;②自观测以来,荣昌井多层水温同震响应方向均为上升,说明单个井水温对不同地震的同震响应存在优势响应方向,水温的同震特征更依赖于井孔自身观测条件的影响;荣昌井水温同震响应优势方向上升可能是地震波的扰动造成井下深部气体释放,并沿裂隙上升进入井含水层系统而引起;③荣昌井水位-水温对中、远场地震的同震为同向上升正相关关系或振荡—上升,对近场地震的同震为水位下降—水温上升的反相关关系,可能是近场地震和中、远场地震引起的水位同震响应变化机制不一致所致;引起荣昌井水温同震变化的地震波能量密度e(r)＞10^-5J/m³,而引起荣昌井水温和水位同震反向变化的地震波能量密度e(r)＞1J/m³。

In this paper,we used the digital minute observation data of water temperature in Rongchang well located in Huayingshan Fault zone of Chongqing city,to analyzed the dynamic characteristics of coseismic and post earthquake response of Rongchang well water temperature to 273 earthquakes(M_S≥7.0 in the world,M_S≥6.0 in Sichuan Yunnan region,M_S≥4.0 in Chongqing and its surrounding areas)from January 2008 to September 2021,in order to study the cause and mechanism of coseismic dominant direction of well water temperature. The following results are obtained:① The water temperature of Rongchang well shows good coseismic and post-earthquake response ability,which can be recorded from both near and far earthquakes. The coseismic response of the water temperature in the well occurs from deep to shallow,in which the response duration is directly proportional to the observation depth,and the response amplitude decreases with the increase of the observation depth. The duration of the coseismic and post-earthquake response of the water temperature of the well is often longer than that of the water level of the same well. ② Since the observation starts,the coseismic response direction of water temperature in Rongchang well keeps increasing,which suggests that the water temperature of a single well has a dominant response direction for the coseismic response of different earthquakes,and the coseismic characteristics of water temperature depend more on the influence of the observation conditions of the borehole itself. The rise of the dominant direction of the coseismic response of the water temperature in Rongchang well may be caused by the disturbance of the seismic wave,which causes a large amount of gas in the deep part of the well to release into the aquifer system along the fractures. ③ The coseismic relationship between water level and water temperature in Rongchang well for medium and far-field earthquakes is mostly positive correlation of synchronous rise or oscillation-rise,and the coseismic relationship for near-field earthquakes is the inverse correlation between coseismic water level decline and water temperature rise,which may be caused by the inconsistent change mechanism of water level coseismic response caused by near-field earthquakes and medium and far-field earthquakes. Finally,the seismic energy density e(r) causing coseismic variation of water temperature in Rongchang well is greater than 10^-5J/m³,while the seismic wave energy density e(r) causing the coseismic reverse change of water temperature and water level in Rongchang well is greater than 1J/m³.

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河北省地震动力学重点实验室开放基金(FZ202103)、中国地震局震情跟踪定向工作任务(2020010318、2021010313)和重庆市地震局科技创新团队共同资助