阿留申群岛地震台站方位角变化及其对横波分裂的影响

Orientation variations of the seismometers in the Aleutian Islands and their impacts on shear wave splitting analyses

  • 摘要: 利用瑞雷波极化分析法计算了阿留申群岛上AK,AT,AV,IM,TA和XJ台网共59个地震台站的方位角及其随时间的变化。结果显示:阿留申群岛大部分台站的方位角与地理北极均存在一个小角度的偏差,极个别台站的偏差角度极大;部分台站的地震仪在摆放过程中受重新定北、安装新仪器等人为因素的影响,方位角大小在前后时段内并不一致。这充分说明台站方位角对横波分裂研究具有重要作用,当方位角偏离地理北极度数较大时,其对横波分裂研究的影响则不可被忽略,需要对地震数据分时段进行相应台站方位角的校正。

     

    Abstract: Rayleigh wave polarization analysis is adopted to calculate the seismometer orientations of 59 seismic stations in the Aleutian Islands including networks AK, AT, AV, IM, TA, and XJ. For most stations, the orientations deviate slightly from the geographical north pole while a few stations show strikingly large misorientations. The misorientations can be caused by many anthropogenic factors, such as the re-orientation after the deployment or the installation of new instruments, which leads to the variations of seismometer orientations during the station operation period. The orientations of the seismometer plays a significant role in seismology studies. For example, if the deviation of the orientation from the geographical north pole is large, it will affect the obtained values of fast orientations of splitting shear waves. Therefore the orientation of the stations need to be corrected for the seismic data by time interval.

     

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