井下记录的PP和SS震相

PP AND SS SEISMIC PHASES RECORDED FROM BOREHOLE

本文在系统分析静海台井下地震记录图的基础上,发现并解决了具有一定实际和理论意义的两个问题:其一是证明了最初误认为是干扰的“双脉冲”图形实际上均是微地震。从而指出研究静海周围地区的地震活动性应考虑微震活动问题。其二确认静海周围地区微震波形的4个主要震相是P、PP、S和SS,并对地面反射波PP和SS能够观测到的条件作了初步分析,其结果进一步说明井下地震记录较之地面记录更为“逼真”,复杂和丰富。

In this paper, two problems with certain practical and theoretical significance are discovered and solved based on systematic analysis of the seismograms recorded from boreholes. First, it has been proved that all the 'double pulses' which had been mistaken for disturbance are actually microearthquakes, so we suggest that the problem of microearthquake activity must be considered, when studying the seismicity in jinghai and surrounding region. Second, four main kinds of seismic phases of microearthquake that occur in Jinghai and surrounding region are considered as P, PP, S and SS and the observational conditions for the surface reflections PP and SS are preliminarily analyzed, The results show further that the borehole records are more 'faithful', complex and rich in details than the surface records.