昭通巡龙强夯土非天然地震记录特征及识别研究

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

通过分析昭通巡龙2022年11月—2023年5月多次重型地面平整机施工和小震级天然地震事件的记录特征及差异后认为:昭通巡龙强夯土事件的P波初动向下、持续时间短、衰减快、P波与S波最大振幅小于天然地震,强夯土事件波形记录的频谱特征与天然地震差异较大,天然地震P波与S波震相明显,强夯土事件震相不明显。可以利用Pg/Sg谱比、交叉Pg/Sg谱比实现强夯土非天然地震和天然地震事件的分类识别。分类结果表明:当频率大于5 Hz时,Pg/Sg谱比判据基本实现天然地震和强夯土事件分类;交叉Pg/Sg谱比判据对应的分类识别正确率为天然地震事件91.3%,强夯土事件90.7%。交叉Pg/Sg谱比判据比单一频带谱比判据能更好地反映天然地震和强夯土事件的特征差异。

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.