COMPREHENSIVE ANALYSIS OF VOLUME STRAIN OBSERVATION DATA IN GUYUAN STATION

The statistical analysis of volume strain data since January in 2008 in Guyuan station was done,including continue rate,daily drift,intrinsic accuracy and noise level etc.The result showed the continue rate,intrinsic accuracy and noise level were all higher,the daily drift was fast.The correlation analysis between the observation data and barometric pressure was done during 4 selected periods and the result showed the observation data was closely related with barometric pressure and there was hysteresis effect for 40 minutes.Removing barometric pressure influence through correlation analysis could pass the intrinsic accuracy test and got significant effects.Combined with earthquake tendency in south of Ningxia,the anomaly characteristics before 4.0 earthquakes was introduced using difference analysis briefly.