少震区前兆异常的特征分析  

Characteristic analysis and precursory anomaly in weak seismic region

作　　者：吴富春[1] 刘春[1] 

机构地区：[1]陕西省地震局,陕西西安710068

出　　处：《地震》2001年第2期41-45,共5页Earthquake

基　　金：地震科学联合基金项目!( 950 74 31 )

摘　　要：以陕西前兆台网 2 4年的资料为基础 ,分析了少震区前兆异常的一些特征。在这个建网以来未发生过 5级以上地震 ,每年平均发生 2～ 3次 3级多地震 ,年最大震级的平均值仅为 3.6级的陕西前兆台网中 ,每年年度会商所提出的各类测项异常比在 1 1 %～ 2 0 %之间 ,综合异常比为 1 5%。这些异常比的变化曲线与陕西省内地震频次和强度变化曲线不同步 ,它们是与地震无关的测值变化 ,可能是未被人们认识的外界干扰 。Based on the data of precursory anomaly observed in Shaanxi Precursory Network, we analyzed the characteristics of precursory anomaly in the regions where there are no or few earthquakes. The ratio of precursory anomaly is between 11% to 20% for different precursory means and the comprehensive ratio of anomaly is 15% in Shaanxi Precursory Network. There is no earthquake with M S ≥5.0 and usually only two to three earthquakes with M S ≥3.0 occurred every year and the average magnitude of maximum earthquakes for every year is M L =3.6. The curve variation between the anomaly ratio, seismic frequency and seismic intensity in Shaanxi region is not synchronal. So, it is concluded that the precursory anomaly is not the earthquake precursor, and it may be the interference unknown or the result of aseismic slipping in crust.

关 键 词：少震区 前兆异常 无震滑动 地震活动性 前兆异常比曲线 前兆台网 

分 类 号：P315.72[天文地球—地震学] P315.5[天文地球—固体地球物理学]