Abstract: Based on the data recorded by 18 ground fluid monitoring stations in Xinjiang Uygur Autonomous Region for 20 years, along the main line of anomalies and earthquake epicenters, the statistics and analysis on characteristics of precursory anomalies of 16 M5 earthquakes, 4 earthquakes with M>7 and 1 M6 strong earthquake swarm are conducted. The results show that the focal, field and remote precursory anomalies are of the following characteristics:    The spatial distribution of anomalies is inhomogeneous, the distribution of anomalous monitoring stations of focal precursors is concentrated, and the anomaly ratio can reach 90%; but the spatial distribution of field precursors is sparse, and the anomaly ratio is about 45%~53%; the spatial distribution of remote precursors is sparser, the anomaly ratio is 25%. Usually, the beginning time is different, most of anomaly time of focal precursors is medium-term; most of anomaly time of moderately strong earthquakes field precursors is medium-short term, particularly short-term; most of anomaly time of strong earthquake's field precursors is medium-term; and most of anomaly time of strong earthquake's remote precursors is medium-term too. The anomaly patterns are different, most of medium-term anomalies of focal precursors and strong earthquake's field precursors show the step-like rising tendency, and most are chemical observational items, the oil-gas wells show blowing. However, the anomalies of moderately strong earthquake's field precursors are short-term, negative ones with obvious amplitude, and show pulse bound, high value rising within short time, step-like change, and the regularity of yearly variation is broken. The remote precursory characteristics of strong earthquakes are medium-term anomalies for few observational stations and observational items; the suddenly ump phenomenon of several observational items exists during impending earthquake, the oil-gas wells also show blowing.

Key words: Focal precursor, Field precursor, Remote precursor, Ground fluid in Xinjiang region