A Method of Removing the Interference from Urban Railway Transit in The Geoelectric Field

Abstract

In recent years, with the development of urban railway transit (URT), interference in the geoelectric field (GEF) has been generated. This brings serious difficulties to the acquisition of earthquake precursors. In this study, by analyzing the spectral features of daily minute-sampling GEF data without and with interference from urban railway transit (URTI) and without one respectively, the Butterworth function was selected as a transfer function for Fourier filtering, and its cutoff frequency was set. A method of removing URTIs (RURTIs) was developed. Then, the RURTI method was used to process the NS, EW and NE GEF data to better recognize the anomaly before the Guye Ms 5.1 earthquake at Yanqing station. Compared with a polynomial-smoothing filtering method, the RURTI method has better performance in improving the signal-to-noise ratio and recognizing preearthquake anomalies. After the differences between the original GEF data and the processed data using the RURTI method were calculated, a method of recognizing the preearthquake anomaly was found.