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地震学的定量研究需要精确的仪器时钟。最近的研究进展表明,可利用背景噪声来检测存在软件/硬件问题的海底地震仪(OBS)或陆上地震仪的台站时钟漂移情况。在稀疏的全球地震台网尺度下,从背景噪声中提取的短周期(<20s)瑞利波信号相对较弱,应用时受到限制。位于几内亚湾的持续稳定的26s固定脉动源,辐射出较强的噪声信号,可以被全球台站记录到,因而可以利用它同步加大距离台站间的时钟漂移情况。本文基于噪声互相关方法,我们尝试运用该26s的脉动信号检测非洲、北美和欧洲等地区地震台站的时钟精度。结果发现TAM,OBN台站的时钟在2002~2009年间相对稳定;CCM台站的时钟在2006~2009年间出现了约1s偏差,并且时钟的漂移量不稳定;KOWA台站的时钟漂移从2012年10月的约150s最大上升至2013年1月的约500s。本文将得到的结果与Stehly等(2007)利用背景噪声方法得到的结果、以及远震P波初至到时残差进行了对比分析。利用本文提出的方法,通过与经精确校正过的陆地台站同步,可校正北大西洋海底地震仪的时钟。
Seismological quantitative research requires accurate instrument clocks. Recent advances have shown that background noise can be used to detect station clock drift for undersea seismographs (OBS) or onshore seismographs in the presence of software / hardware problems. At sparse global seismograph scales, the short-period (<20s) Rayleigh signal extracted from the background noise is relatively weak and is limited in application. The constant, steady 26-s fixed pulsation source in the Gulf of Guinea radiates a strong noise signal that can be recorded by the global stations, thus allowing it to synchronously increase the clock drift between stations. In this paper, based on the noise cross-correlation method, we try to use 26s pulsation signal to detect the clock accuracy of seismic stations in Africa, North America and Europe. The results show that the clocks of TAM and OBN stations are relatively stable from 2002 to 2009; the clocks of CCM stations fluctuate about 1 second between 2006 and 2009, and the clock drift is unstable; and the clock drift of KOWA stations fluctuates from 2012 The maximum rise in October of about 150s to about 500s in January 2013. In this paper, the results obtained are compared with the results obtained by Stehly et al. (2007) using the background noise method and the first arrivals residual wave of teleseismic P waves. Using the method proposed in this paper, the clock of the North Atlantic seabed can be calibrated by synchronizing with precisely calibrated land stations.