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反演高频率(≥2Hz)的瑞雷波的相速度可得到分层地球模型从地表到地下30m以内的剪切(S)波速度。如果已知S波速度VS、压缩(P)波速度VP和瑞雷波速度,通过反演瑞雷波衰减系数就可以获得分层地球模型的P波品质因子QP和S波品质因子QS。模拟结果证明,根据瑞雷波衰减系数反演品质因子QS是可行的。当VS/VP达到0.45时,不能忽略QP对瑞雷波衰减系数的贡献,这种情况在近地表构造中并非罕见。从某些地质构造中的瑞雷波衰减系数反演得到QP是可能的,这是一种不同于一般认为的观点,即相对于P波的品质因子QP,瑞雷波的衰减系数对S波的品质因子QS更为敏感。在亚利桑那沙漠,采集了60道的面波数据。对一个层厚度超过20m的10层模型,首先利用多道面波分析(MASW)方法反演数据得到S波速度,然后通过反演衰减系数确定品质因子。
Retrieving the phase velocity of a Rayleigh wave with a high frequency (≥2 Hz) yields the shear (S) wave velocity of the layered earth model within 30 m above the ground. If the S-wave velocity VS, the compressional (P) wave velocity VP and the Rayleigh wave velocity are known, the P-wave quality factor QP and the S-wave quality factor QS of the layered earth model can be obtained by inverting the Rayleigh attenuation coefficient. The simulation results show that it is feasible to invert the quality factor QS based on the Rayleigh attenuation coefficient. When the VS / VP reaches 0.45, the contribution of QP to the Rayleigh attenuation coefficient can not be neglected, which is not uncommon in the near-surface structure. It is possible to derive QP from the inversion of the Rayleigh attenuation coefficient in some geological formations. This is a different view from the general belief that the attenuation factor of the Rayleigh wave versus the S wave The quality factor QS is more sensitive. In the Arizona desert, 60 surface wave data were collected. For a 10-layer model with a layer thickness of more than 20m, the S-wave velocity is first retrieved by using the Multi-surface Wave Analysis (MASW) method, and then the quality factor is determined by inverting the attenuation coefficient.