短周期仪器记录在远震分析中的应用

SEISMOGRAMS RECORDED BY SHORT PERIOD INSTRUMENTS USED IN DISTANT EARTHQUAKE ANALYSIS

地震泼由多种频率成份组成,在其传播过程中。由于地球介质的滤波作用,随着传播距离的增大。高频成份逐渐被衰减。周期越大的成份传播越远。因此,在地震观测上,不同频带的地震仪用于观测不同震中距范围的地震,使仪器较好地响应,就我国台网而言,短周期仪用于地方震、近震的监测,中长周期仪和长周期仪用于远震,极远震的监测,其中长周期仪偏重于记录极远震。但作者在实际分析工作中注意到,短周期仪的记录应用于远震,极远震的分析,显示出独特的作用,充分挖掘和利用短仪资料,将会更加丰富远震、极远震的震相资料。本文以高台地震台的资料为依据,从震中距和震级角度,与中长仪和长仪作比较,对短仪记录远震、极远震的震相及特征作了统计分析与初步探讨,并对新疆地区“影区”地震S波的记录、日本地区地震_PPcP等震相的出现提出了现象的存在,给出了相应的观测结果,以待步一步研究。

Usually, we only used the seismograms recorded by medium-long and long period seismic instruments for analysing distant and very distant earthquakes. But the writer of this paper noted that the short period recording is very good for the analysis of some phases on seismograms of distant and vere distant earthquakes. This paper uses the recording at the Gaotai seismic station to compare recording characteristics be tween seismograms by short and long (medium-long) period instruments, and discusses some waveform characteristics and analysis methods at different epicentral distances for distant and very long distant earthquakes recorded with short period instruments. The writer discusses especially the cases of some earthquakes in particular regions, too for example, S-wave recording of the earthquakes in the 'Shadow zone' pPcP, sPcP and sScS-wave recording of the earthquakes in the Japan region, and listed some data about these seismic waves.