2014年安徽霍山MS4.3地震前地下流体典型异常特征分析

Analysis of Typical Anomalies Observed from Underground Fluid before 2014 Huoshan M S4.3 Earthquake

通过对2014年4月20日安徽霍山MS4.3地震前地下流体异常进行回溯性分析,总结了流体异常特征。结果显示,在时间上,流体异常具有配套性、阶段性特征,震前11个月异常月频次逐渐增加;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;在空间上,流体异常主要集中在震中200km范围内,且外围流体异常主要表现为趋势上升或低值,震中附近流体异常表现为突升。震前流体异常还与测项有关,水温、水化测项映震效果较好,水氡、氢气突升异常短临意义明显。

After reviewing all precursory anomalies from observation of underground fluid before 2014 Huoshan MS4.3 earthquake we summarized the general characteristics of these anomalies in temporal and space.The results indicate that the overall precursory anomalies are characterized by compatibility.Temporally,the number of abnormal factors began to increase in about eleven months before earthquake,and the growth rate of the number of abnormal factors speeded up in about three months before earthquake.In the impending stage in about 1.5 months before earthquake,however,some anomalies disappeared,and some abnormal intensity decreased.Spatially,the anomalies mainly concentrated in a distances about 200km from the epicenter.Particularly,the fluid anomalies mainly showed a sudden rise near the epicentral region but a gentle rising in distal region Moreover,the precursor anomaly varies with different observation methods.The effect of fluid temperature,geochemistry such as radon and hydrogen is significant in corresponding to the occurrence of earthquake.