山西省测震台站纵波段初至前小振幅波成因浅析
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摘要
通过查看山西测震数字台网2009年1400个记录清晰事件波形,发现在ML<4.5的事件中有158次初至波前出现奇异小信号,在ML≤2.8的微小地震中小振幅波记录更加清晰。统计发现,这些小信号出现在使用GURALP公司生产的CMG-3ESPC地震计、CMG-DM24数据采集器的9个子台记录中,而其它型号的仪器系统中均未见。小信号主要集中在震中距<60km的近台记录初至前0.2~0.7s,经FFT分析,得出小信号频率集中在45~50Hz。认为该频率的信号在CMG仪器系统上有记录,主要是因为港震等其他类型的仪器系统可能将这部分频率成分过滤掉了,而它们恰好处在CMG仪器系统的记录范围内。
The review of the clear waveforms of the 1400 earthquakes recorded by the Shanxi Digital Seismic Network in 2009 reveals that abnormal weak signals appeared before the first arrivals of the 158 events with M < 4.5,including those micro-events of ML ≤2.8 with clearer weak signals.These weak signals were recorded by the GURALP's CMG-3ESPC seismometers and CMG-DM24 data acquisition recorders at the 9 stations,while there were not such signals in other instrumental systems.The FFT analysis finds that the frequency of weak signals ranges from 45 Hz to 50 Hz.It is regarded as the results of the superposition of signals in different frequencies.The further analysis leads to the conclusion that it is also relative to the focus and the crustal media near the station.
引文
陈运泰、吴忠良、王培德等,2000,数字地震学,47~60,北京:地震出版社出版。

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