The importance of the surface or interface P wave in near-earthquake studies
The importance of the surface or interface P wave in near-earthquake studies
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DOI：
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发表时间：
1978-10
影响因子：
3
通讯作者：
M. Bouchon
中科院分区：
文献类型：
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作者：
M. Bouchon
对二维位错传播源辐射的表面P波进行了研究。在半空间地震断层的近场计算的理论地震图显示出意想不到的强地表P脉冲。对于所研究的构造，该波是水平地震记录上的突出相位。它对垂直运动的影响很小，这可能导致水平和垂直地震记录明显不相关。在水平分量上得到的SP脉冲看起来与无限介质溶液的剪切脉冲非常相似。这一事实，再加上S波在超过临界距离后振幅大幅减小，很容易导致将地表P脉冲误认为是直接横波。纵波速度大于源介质横波速度的表层的存在对表面P波的强度没有明显的影响。在低速沉积层中，表面P波被界面P波取代，界面P波在层厚较小的情况下可以有效地向表面辐射。
abstract A study of the surface P wave radiated by propagating two-dimensional dislocation sources is presented. Theoretical seismograms computed in the near-field of an earthquake fault located in a half-space show an unexpectedly strong surface P pulse. For the configurations studied, this wave is the prominent phase on the horizontal seismogram. It has little effect on the vertical motion, which may result in apparently uncorrelated horizontal and vertical seismograms. The SP pulse obtained on the horizontal component looks very similar to the shear pulse of the infinite medium solution. This fact, combined with the large reduction in amplitude of the S wave past the critical distance, may easily result in the misidentification of the surface P pulse as the direct shear wave. The presence of a surface layer with compressional velocity larger than the shear velocity of the source medium is not seen to affect significantly the strength of the surface P wave. In the case of a low-velocity sedimentary layer, the surface P wave is replaced by an interface P wave which can radiate efficiently to the surface provided that the layer thickness is small.