Research on the characteristics and identification of non natural earthquake records of Zhaotong Xunlong strong rammed soil

This article analyzes the recorded characteristics and differences of multiple heavy ground leveling machine construction and small magnitude natural earthquake events from November 2022 to May 2023 in Zhaotong Xunlong. Analysis shows that the initial motion of P-wave of the Zhaotong Xunlong strong rammed soil event is downward, with short duration, fast attenuation, and the maximum amplitude of P-wave and S-wave is smaller than that of natural earthquakes. The spectral characteristics recorded by the waveform of strong rammed soil event are significantly different from those of natural earthquakes, and the seismic phase P-wave and S-wave of the natural earthquake is obvious, while the seismic phase of the strong rammed soil event is not obvious. Utilizing Pg/Sg spectral ratio and cross Pg/Sg spectral ratio achieves classification and recognition of non natural earthquakes and natural earthquake events in dynamically compacted soil. The classification results indicate that when the frequency is greater than 5 Hz, the Pg/Sg spectral ratio criterion basically achieves the classification of natural earthquakes and strongly compacted soil events; The classification recognition accuracy corresponding to the cross Pg/Sg spectral ratio criterion is 91.3% for natural earthquake events and 90.7% for strong compacted soil events. The cross Pg/Sg spectral ratio criterion reflects the characteristic differences between natural earthquakes and strongly compacted soil events better than the single frequency band spectral ratio criterion.