Abstract: During June and July of 2003, two earthquakes with M_L4.8 occurred in succession near Xiaomiao seismological station, Xichang, Sichuan Province. The epicenters are 8~12 km away from the station. Before the two earthquakes, two particular anomalies were detected by an auxiliary water meter laid in a strain observation well of the station. As for the two anomalies, one water level shows the rising trend was changed into ascending; the other shows dramatically change in diurnal fluctuation, which seems like solid tide effect. These types of anomalies are seldom reported abroad and at home. They have close relation with source evolution and can be considered as source precursor anomaly.

Key words: Well water level, Source precursor anomaly, Xiaomiao seismological station, Solid tide