小庙台应变观测孔水位的源兆异常

2003年6~7月在四川省西昌市小庙地震台附近连续发生2次M_L4.8地震, 台站距震中为8~12 km。 这次地震前在该台地应力观测孔的辅助水位观测中, 记录到了二次特殊的异常现象。 异常表现为: 一是改变水位上升趋势为下降; 二是表现为日变幅度变为显著, 其形态似固体潮效应。 这类异常国内外尚未见报道, 研究认为这与震源过程密切有关, 可作为源兆异常。

Source precursor anomaly of water level in strain observation well at Xiaomiao Station

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.