关键词: 少震区, 前兆异常, 无震滑动, 特征分析

Abstract: Based on the data of precursory anomaly observ ed in Shaanxi Precursory Network, weanaly zed the characteristics of precurso ry anomaly in the regions where there are noorfew earthquakes. The ratio of precursory anomaly is betw een 11% to 20% for different precursory means and the comprehensive ratio of anomaly is 15% in Shaanxi Precursory Netwo rk. There is no earthquake wi th MS ≥ 5.0 and usually only two to three earthquakes with MS ≥ 3.0 occurred ev ery year and the average magni tude of maximum earthquakes for ev ery year is ML = 3.6. The curvevariation betw een the anomaly ratio, seismicf requency and seismic intensi ty in Shaanxi region is not sy nchronal. So, it is concluded that the precurso ry anomaly is not the earthquake precursor, and it may be the interference unknownor the result of aseismic slipping in crust.

Key words: Weak seismic region, Precursory anomaly, Aseismic slipping, Characteristic analysis