北京塔院井数字化观测水温的同震效应研究

基于北京塔院井数字化水温观测资料，分析了远震引起的水温同震效应，注意到塔院井水温同震变化总是具有下降－上升－恢复的过程，不受地震方位和震源机制的影响；水温同震下降幅度随震级的增大而增大，随震中距的增大而减小， 三者之间有较好的关系；震后水温后效恢复上升幅值受水位动态影响. 最后，对塔院井水温同震效应机理进行了探讨，初步研究结果显示，井孔中的水体受震荡激发而加速对流与掺混是导致水温先下降的主要原因:当井水受到地震波的作用时，对流加速，井内深部较热的水体上涌， 而浅部较冷的水体下沉，水温探头将先观测到温度下降现象； 震后水震波逐渐平息，探头附近井水温逐步恢复上升. 

COSEISMIC EFFECTS OF WATER TEMPERATURE BASED ON DIGITAL OBSERVATION FROM TAYUAN WELL, BEIJING

On the basis of digital records from Tayuan well, we study coseismic effects of water temperature caused by remote earthquakes. The records show that the water temperature changes are consistently following the process of drop-rise-recovery regardless of focal mechanism or epicentral directions. The step amplitude of water temperature increases with the increase of earthquake magnitude, and decreases with the decrease of epicentral distances. They have rather well correlation. Water temperature rising after earthquake is influenced by water level variations. Finally, the mechanisms of coseismic effects of water temperature have been discussed. Preliminary study shows that accelerated convection and mixing of different temperature water in virtue of seismic wave are the main causes of water temperature drops. Seismic wave accelerates water convection, which causes warm water to move up from deeper part of the well and cold water to go down from the upper part. Temperature probe will detect water temperature drops at early stage. After the occurrence of earthquake, as the fluctuation of water level gradually quiets down, water temperature near the probe begins to rise.