Recognition of earthquakes and explosions based on generalized S transform

In order to further enhance the ability of regional seismic network in distinguishing between natural earthquakes and artificial explosion events, the generalized S-transform method was used in this paper to study the waveform records of the explosions and the natural earthquakes occurred around Sanhe quarry of Hebei Province, and then the differences of time-frequency spectra between earthquakes and explosions were summarized. Affected by the focal mechanism, the time-frequency spectrograms of natural earthquakes show a wider frequency band range, and more complex distribution of energy clusters than those of artificial explosions. In order to eliminate the influence of epicentral distance, the time-frequency spectra obtained in this paper are saved as gray-scale images with the same size, and a new recognition criterion “the second-order moment of spectrum” is obtained by mathematical method. The test of the known earthquake and explosion events in Sanhe area suggest that the recognition rate of the second-order moment of spectrum for waveform records on single station reaches up 91%, and the recognition rate is more than 98% after taking the average of multiple stations, which indicates that the new recognition criteria has a good application prospect.