Abstract:In order to study whether the electromagnetic signal can be used as a reliable earthquake precursor signal, an electromagnetic sensing probe based on inductive magnetic sensor for earthquake monitoring is designed. The probe is composed of a signal processing and an acquisition circuit, which can support electromagnetic signal acquisition in very low frequency (VLF) and ultra low frequency (ULF) from 10 Hz~ 10 kHz in a wide dynamic range 0. 1~ 1 000 nT. The sensitivity of the probe is greater than 20 mV/ nT@ 0. 1 Hz~ 10 kHz, 18-bit resolution. Besides, the probe has passed many reliability tests and has been applied to 221 stations including the Sichuan and Yunnan National Test site for electromagnetic monitoring. Field observation experiments show that the probe can capture a highly correlated electromagnetic signal effectively.