基于标准时频变换的上海地区地震与爆破识别

Recognition and Analysis of Earthquake and Blasting in Shanghai Area based on Standard Time-frequency Transform

以上海地区记录到的天然地震和“4·20”上海中环中心爆破、“4·26”浦东爆破为例进行标准时频变换分析,并对得到的标准时频谱特征进行研究。通过对时频谱进行对比可看出:经过NTFT变换后的数据相对于小波变换、时频域的分辨率有显著的提升,可更为清晰地展示出地震信号和背景噪声的信号特征,在一定程度上,能对不明显的地震波形,甚至被噪声淹没的地震信号进行有效的识别;上海地区天然地震与爆破事件的频率均主要分布在20~40 Hz范围内,频带范围差异不大;天然地震能量信号多集中在20 Hz附近,而爆破事件能量信号则大致集中在30~40 Hz之间;天然地震能量分布呈现“多峰”特征,而爆破事件则表现出相对“少峰”,主要呈现出高能量、小范围冲激形式的特点。

This paper takes the natural earthquakes recorded in the Shanghai area,the"4·20"Shanghai Central Blasting and the"4·26"Pudong Blasting as examples to analyze the standard time-frequency transform,and study the obtained standard time spectrum characteristics.By comparing the time-frequency spectrum,it can be seen that the resolution of the time-frequency domain of the NTFT-transformed data is significantly improved compared to the wavelet transform,and the signal characteristics of the seismic signal and background noise can be displayed more clearly.To a certain extent,it can effectively identify unobvious seismic waveforms and even seismic signals that are submerged by noise.The frequencies of natural earthquakes and blasting events in Shanghai are mainly distributed in the range of 20~40 Hz,with little difference in frequency range;natural seismic energy signals are mostly concentrated around 20 Hz,while blasting event energy signals are roughly concentrated between 30~40 Hz.Natural seismic energy distribution presents"multi-peak"characteristics,while blasting events show relatively"few peaks",mainly showing the characteristics of high-energy,small-scale impulse forms.