地震工程学报2025，Vol.47Issue(3)：727-740,14.DOI:10.20000/j.1000-0844.20240130001
2022年泸定Ms6.8地震前超低频事件的检测分析
Detection and analysis of very low frequency earthquakes before the 2022 Luding Ms6.8 earthquake
摘要
Abstract
On September 5,2022,an Ms6.8 earthquake struck Luding County,Ganzi Prefecture,Sichuan Province.Slow earthquakes manifested as very low frequency earthquakes occurring in the source region before the Luding earthquake hold significant implications for understanding the source physical processes of the mainshock.This study employs the Hilbert transform and short-time Fourier transform(STFT)to detect very low frequency earthquakes preceding the main-shock,with preliminary analyses of their recording stations,spectral characteristics,and tempo-ral features.The results indicate the following:(1)A total of 14 very low frequency earthquakes were detected before the mainshock,and their vertical and horizontal components could be effec-tively detected,with superior detection performance in the vertical component.(2)Events with large amplitudes and long durations were better identified using the Hilbert transform,whereas those with small amplitudes,short durations,and overlapping waveforms were effectively detec-ted using STFT.(3)A total of 67.7％of the stations successfully recorded all events,demonstra-ting strong observational reliability.The very low frequency earthquakes exhibited distinct spec-tral peaks within a relatively low-frequency range(0.06-0.16 Hz),markedly differing from the frequency bands of natural earthquakes.The event with the largest amplitude occurred 18 h be-fore the mainshock,followed by an increasing frequency of events accompanied by heightened small earthquake activity.This pattern may reflect a gradual release of crustal stress through very low frequency earthquakes and minor earthquakes until the occurrence of the mainshock.关键词
超低频地震/希尔伯特变换/短时傅里叶变换/泸定Ms6.8地震Key words
very low frequency earthquakes/Hilbert transform/short-time Fourier transform/Luding Ms6.8 earthquake分类
天文与地球科学引用本文复制引用
张晓阳,邓津,李淑婷..2022年泸定Ms6.8地震前超低频事件的检测分析[J].地震工程学报,2025,47(3):727-740,14.基金项目
甘肃省地震局地震科技发展基金(2020GZ02) （2020GZ02）
中国地震局兰州地球物理国家野外观测站项目(2021Y02) （2021Y02）
甘肃省青年科技基金(22JR11RA089) （22JR11RA089）
甘肃省青年科技基金(22JR5RA827) （22JR5RA827）
