2011年安徽安庆M4.8地震前苏、皖典型前兆异常特征分析

Analysis on Characteristics of Precursory Anomalies of the 2011 Anqing M4.8 Earthquake in Anhui and Jiangsu

通过对2011年安徽安庆M4. 8地震前震中400 km范围内前兆异常进行回溯性分析,总结了前兆异常特征。结果显示:时间上前兆异常具有显著的群体性、协调性等阶段性特征,震前12个月异常月频次逐步增加;震前3个月异常月频次加速上升,进入临震阶段;震前1. 5个月,部分异常结束,异常月频次转折下降。空间上,异常广泛分布,但主要集中在250 km空间范围内,异常具有迁移性特征。水位、水温测项映震效果较好,水位突降异常短临意义明显。

Analyzing all the precursory observation data in the range of 400 km rang from the epicenter before the Anhui Anqing M 4.8 earthquake occurred on Jan.19,2011,we found the precursory anomaly information and summarized the characteristic of them.The results show that the precursory anomaly has the characteristic of group,coordination etc..The number of abnormal items began to increase about a year before the earthquake.The growth rate of the number of abnormal item began to speed up about 3 months before the earthquake.In the impending stages of about 1.5 months before the earthquake,the abnormal monthly frequency turned down,while the partial precursor trend anomalies began to turn over.The anomalies distributed extremely wide in spatial,and mainly concentrated in a distance of 250 km from the epicentre,which showing the characteristics of mobility.The effect of corresponding earthquake of water level and water temperature is very well,and the short impending significance of water level drop is important.