2024年2月24日安徽肥东发生ML 3.5地震，选取淮安地震监测中心站井下地震计及淮阴地震监测中心站地表地震计记录波形进行常规滤波及噪声分析，采用深度神经网络去噪方法将地震波形和噪声数据分离，并进行时频分析，结果表明：①基于原始信号测定震级，地表地震计所测定震级更大；②经去噪处理，地表与井下地震计测定震级相近，但波形成分存在差异，其中井下地震计水平分量高频成分更多，而地表地震计则垂直分量高频成分更多，且P波发育，振幅大，推测为地面土层对地震波的放大作用所致；③地表地震计噪声记录含高频成分，推测为环境背景噪声，而井下地震计记录地震时产生的次生噪声频率和强度呈逐渐衰减趋势，据噪声形态判定，推测为井下地震计弹性支架受地震波场作用产生共振所致，说明所处空间不同，噪声来源发生了变化。
ML 3.5 earthquake occurred in Feidong, Anhui Province on February 24, 2024. The waveforms recorded by underground seismograph and surface seismograph at Huai’an Earthquake Monitoring Center Station were selected for conventional filtering and noise analysis. The seismic waveforms and noise data were separated by deep neural network denoising method, and time-frequency analysis was carried out. Results shows that,① Based on the original signal, the magnitude measured by the surface seismometer is larger;② After denoising, the seismic magnitude measured by surface seismometer and underground seismometer is similar, but the waveform components are different. The horizontal component of underground seismometer has more high-frequency components, while the vertical component of surface seismometer has more high-frequency components, and the P wave is developed and the amplitude is large, which is presumed to be caused by the amplification of seismic waves by the ground layer;③ The noise recorded by the surface seismometer contains high-frequency components and is presumed to be environmental background noise, while the frequency and intensity of the secondary noise generated by the underground seismometer when recording the earthquake show a gradually decreasing trend. According to the noise pattern, it is presumed to be caused by the resonance of the elastic support of the underground seismometer under the action of seismic wave field, indicating that the noise source has changed in different spaces.
2024,45(6): 14-20
DOI：10.3969/j.issn.1003-3246.2024.06.002
作者简介：李子威（1993—），男，助理工程师，主要从事地震监测工作。E-mail：412707469@qq.com
参考文献：
李留藏. 井下地震计的软定向[J]. 地震地磁观测与研究，1992，13（4）：57-62.
仇中阳，毛华峰，陈健，等. 苏北测震台网地面和井下地震记录波形频谱分析[J]. 地震地磁观测与研究，2014，35（3）：105-111.
王俊国. 深井观测地震波分析（讲座）[J]. 地震地磁观测与研究，1990，11（6）：51-77.
薛志照. 天津地区平原地面、井下与山区的地震记录特征[J].地震，1987，7（2）：24-31.
张少泉，杨懋源，郭建民，等. 深井观测地震波的研究[J]. 中国地震，1992，8（1）：83-94.
Zhu W Q, Mousavi S M, Beroza G C. Seismic Signal Denoising and Decomposition Using Deep Neural Networks[J]. IEEE Transactions on Geoscience and Remote Sensing, 2019, 57(11): 9 476-9 488.
