Determining source of unidentified sound in Tongling area based on seismic event recognition system

In recent years, multiple unidentified sounds have been heard in the Tongling area, and significant vibrations have been felt within structures. To conduct a time-frequency analysis of these unidentified sounds, this study used the time-frequency analysis method in the seismic event recognition system (SERS) developed by the Non-Natural Earthquake Research Laboratory of the Institute of Geophysics, China Earthquake Administration. Through using the SERS, a comparative analysis of time-frequency data and waveform characteristics was conducted between unidentified sound and natural earthquakes, mine explosions, and a chemical plant explosion event in the Tongling area. It was preliminarily determined that the unidentified sound originated from the ground or above. Field visits and investigations showed that when the unidentified sound occurred, no explosions, geological disasters, or other safety production accidents were observed in the city. It was thus concluded that the unidentified sound event was caused by human activity on the ground (or surface). This study provides a reference for using SERS to analyze the source of other non-natural earthquakes.