Interference analysis of the cave extensometer at Yichang seismic station

The new SS-Y extensometer has been in operation for 10 years at Yichang seismic station. Data obtained by the extensometer over the period of 2014 to 2022 at Yichang seismic station were analyzed using the Venedikov harmonic analysis method. The results showed that the internal quality of the data was good. The values of the tide factor of M2 wave of the two components were much greater than 1. The observation accuracy of the NS component is higher than that of the EW component. According to the geophysical network observation data tracking and analysis platform, it was found that there were various types of interference of SS-Y extensometer over the period of 2014 to 2022. After comprehensive analysis, it can be summarized into the influence of four categories of interference factors (observation system, natural environment, site environment and human interference), and the curve was mostly characterized by sudden jumps, steps, breaks, error data, synchronous trend changes and so on. Such as, after filtering processing of the site environmental interference occurred on February 21, 2021, the two components can be clearly recorded to the sharp pulse explosion interference. The classification and screening of these interference characteristics can provide a reference for the accurate identification and abnormal determination of the station data in the future.