Seismic analysis and amplitude-style spectrum ratio study of the 21 March blast at Xiangshui

The P/S-style spectral ratio method is used to process and analyze the records of several stations with high SNR in Xiangshui explosion. An earthquake that occurred about 7 kilometers away from it on January 19，2013 was selected as the comparison event. In the frequency range of 2—15 Hz，for more than 90% stations，the P/S amplitude spectrum ratio of explosion is greater than 1，and the value of natural earthquake is less than 1，while it reaches 100% in the range of 4—15 Hz. In order to further verify the feasibility of this method in judging explosions and earthquakes，this paper calculated the Tianjin Port explosion on August 12，2015，and obtained the same results. This study provides a case study for using P/S-style spectral ratio method to verify low magnitude explosion. At the same time，this paper analyzes the waveform characteristics and spectrum characteristics of the Xiangshui explosion. We concluded that the seismic phase of this event is relatively single，which is similar to an ordinary blasting record，and there is no low-speed air-pressure and ground coupled Rayleigh wave as in the Tianjin Port explosion. And the event has two main frequencies，which are between 0.2—1 Hz and 4—10 Hz respectively.