城市高频地震背景噪声差异性分析  

Analysis on the difference of high-frequency seismic ambient noise in cities

作　　者：孙冬军 刘芳[1,2] 王鹏 SUN Dongjun;LIU Fang;WANG Peng(Shanghai Earthquake Agency,Shanghai 200062,China;Shanghai Sheshan Geophysical National Field Observation and Research Station,Shanghai 200062,China)

机构地区：[1]上海市地震局,上海200062 [2]上海佘山地球物理国家野外科学观测研究站,上海200062

出　　处：《地震地磁观测与研究》2024年第5期80-88,共9页Seismological and Geomagnetic Observation and Research

摘　　要：选取2023年1月1日—28日上海佘山地震台、北京白家疃地震台和湖北恩施地震台连续波形垂直分向记录,分析不同城市人为噪声差异性,结果表明:在研究时段,对于各台每周背景噪声水平结果,上海佘山台和北京白家疃台周五、湖北恩施台周三背景噪声水平偏低;在4—14 Hz频段,不同区域地震背景噪声春节期间显著下降,其中佘山台均方根位移下降约0.4 nm,白家疃台均方根位移下降约0.2nm,恩施台均方根位移下降约3.5nm;在0.1—0.2Hz频段,远震事件造成归一化位移的显著变化,其位移变化持续时间可直观反映地震持续时间,进而反映各地震的大小差异。对于人类活动对台站背景噪声的影响,分析认为:3个台站中,北京白家疃台高频背景噪声干扰最小;f=2 Hz,上海佘山台背景噪声水平偏高;机械化频率f≥5 Hz,湖北恩施台背景噪声水平更高。Selecting continuous waveforms of vertical component from SSE,BJT,and ENS seismic stations from January 1st to 28th,2023,we analyzed the differences in human-induced noise in different cities.The results show that in the study period the seismic ambient noise level of SSE and BJT is lower on Friday and the level of ENS is lower on Wednesday;in the frequency range of 4-14 Hz,the seismic ambient noise level of different regions significantly decreased during the Spring Festival,with the root-mean-square displacement of SSE seismic station decreasing by about 0.4 nm,the root-mean-square displacement of BJT seismic station decreasing by about 0.2 nm,and the root-mean-square displacement of ENS seismic station decreasing by about 3.5 nm;in the frequency range of 0.1-0.2 Hz,the significant change in normalized displacement caused by distant earthquake events can be observed,and the duration of displacement change can intuitively reflect the duration of the earthquake,thereby reflecting the differences in the magnitude of the earthquakes.For the influence of human activities on the seismic ambient noise of the stations,the analysis shows that:among the three stations,BJT seismic station has the least high-frequency seismic ambient noise interference;at f=2 Hz,the seismic ambient noise level of SSE seismic station is higher;at mechanical frequency f≥5 Hz,the seismic ambient noise level of ENS seismic station is higher.

关 键 词：背景噪声 噪声功率谱密度 均方根位移 归一化位移 

分 类 号：P315[天文地球—地震学]