2011年安庆MS4.8地震前地下流体典型异常特征及机理研究

摘要

This paper summarized and analyzed typical underground fluid anomalies appeared before Anqing Ms4.8 earthquake occurred on Jan.19th,2011.The results show that there are many anomalies before the earthquake.According to time scale,it includes medium-term trend anomalies and short-term anomalies.They also have certain regularity on spatial evolution.During medium-term stage,it has two types of anomalies,one is water level anomalies and the other is water temperature anomalies.Water level anomalies scattered in the range of 100～400 km,and the water level of outlying wells show rising trend,and the water level of wells close to epicenter show downward trend.And water temperature anomalies are distributed in the range of 150 km.During short-term stage,anomalies are widely distributed along Tanlu fault.Moreover,they migrated far from epicenter in short-term stage and migrated back near to the epicenter in impending-term stage.%对2011年1月19日安庆MS4.8地震前出现的地下流体典型异常进行了总结分析.结果表明,安庆地震前出现了地下流体群体性异常,这些异常在时间进程上,可分为中期趋势背景异常和短临异常.从空间演化过程上看,也具有一定的规律性.在中期趋势背景阶段,异常可分为两类,一种是水位群体趋势转折异常,另一种是水温异常.其中水位异常广泛分布于震中100～400 km范围内,且外围流体井水位表现为趋势转折下降,近震中附近流体井水位表现为趋势转折上升.水温异常主要分布在震中150 km范围内.在短临阶段,异常沿郯庐断裂带分布较广,且有沿着郯庐断裂带先向远离震中的方向迁移,在临震阶段向震中回迁的特点.