江苏东海深井观测地震波形及其信噪比研究  

Seismic waveforms and their signal-to-noise ratios of borehole observation in Donghai station,Jiangsu Province

作　　者：徐纪人 李海兵[1,2,3] 曾祥芝 赵志新[1,2,3] Xu Jiren;Li Haibing;Zeng Xiangzhi;Zhao Zhixin(Jiangsu Donghai Crustal Activity in Continental Deep Hole National Observation and Research Station,Jiangsu Donghai 222300,China;Key Laboratory of Deep-Earth Dynamics,Ministry of Natural Resources,Beijing 100037,China;Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China)

机构地区：[1]江苏东海大陆深孔地壳活动国家野外科学观测研究站,江苏东海222300 [2]自然资源部深部地球动力学重点实验室,北京100037 [3]中国地质科学院地质研究所,北京100037

出　　处：《地震学报》2022年第6期1007-1018,共12页Acta Seismologica Sinica

基　　金：国家自然科学基金(41374052);国家地质调查局科学基金(J1901);区域地质调查项目(D1911)联合资助.

摘　　要：为了探索在高噪声干扰地区获取高信噪比地震信息的有效途径,本文分析了我国第一个超深井地震观测站江苏东海地壳活动国家野外科学观测研究站设置在地面与井下三个不同深度处的地震仪所记录的波形及其信噪比特征。结果显示:由于观测研究站周围强烈的噪声扰动,地面地震仪记录中无法识别M_(L)0.8地方震波形,而深井地震仪可清晰地记录到该小震波形,且深井地震仪可观测到较地面地震仪更多的零级或负震级地震;井下三组不同深度地震仪所记录波形的信噪比均远高于地面地震仪,且不同深度地震波形信噪比的平均值随仪器深度的增大而增加。井下1559.5 m处的地震仪的波形平均信噪比为69.20 dB,2545.5 m处的信噪比达到74.15 dB,均达到高保真波形的信噪比值,这说明1500 m深处地震仪所观测到的波形可以有效地避免地面干扰,因此深井地震观测能够提供高信噪比的波形资料,为研究震源过程和场地效应等提供真实可靠的基础资料,这也预示着深井观测将促进深井地震学的研究与发展。The Jiangsu Donghai Crustal Activity in Continental Deep Hole National Observation and Research Station(Donghai station for short)is the first deep borehole seismic observation station in China.In order to explore an effective way to observe seismic information with high signal-to-noise ratio in high noise interference areas and to carry out the study on the borehole seismology,this paper analyzed the waveform characteristics and signal-to-noise ratios of waveforms recorded by a seismometer on the ground and three borehole seismometers at different depths underground in Donghai station.The results show that the waveform of a M_(L)0.8 local event cannot be recognized on the seismogram of the seismograph on the ground due to the strong non-seismic noise disturbance around the Donghai station.However,the waveforms of the M_(L)0.8 event can clearly be recognized on the seismograms of the three deep borehole seismographs.Furthermore,the earthquakes with zero magnitude or weaker negative magnitude recorded by the deep borehole seismographs are also more than those recorded by the seismograph on the ground.Meanwhile,the signal-to-noise ratios of waveforms recorded by borehole seismometers at three different depths are much higher than those recorded by the seismometer on the ground;moreover,the average signal-to-noise ratios of waveforms increase with the depths of observation instruments in the borehole.The average signal-to-noise ratio of the waveforms recorded by the seismograph at 1559.5 m depth underground is 69.20 dB,and that of the seismograph at 2545.5 m depth is 74.15 dB.Both of the two ratios reached the signal-tonoise ratio value of high fidelity waveform.Therefore,the observation data of seismograph at about 1500 m depth can effectively avoid the interference on ground and record waveform with high signal-to-noise ratio.Such waveforms provide real and reliable data for the study on source process and site effect,promoting the development of deep borehole seismology.

关 键 词：东海深井观测站 深井地震学 微小地震 波形保真度 波形信噪比 

分 类 号：P315.3[天文地球—地震学]