Acoustic reflectivity from water-alpha Quartz boundary and double Schoch shift

In this experiment, we measured acoustic reflected wavefield from water and z-cut alpha quartz interface in wide azimuthal and incidental directions. This unique dataset was collected at Experimental Geophysics Group at the University of Alberta, with the large transmitter and fine receiver with the resonant frequency of 0.7 MHz and the temporal sampling of 10ns, the incident angular sampling of 0.25 degrees and azimuthal sampling of 10 degrees. Measured acoustic reflectivity indicates double Schoch shift and null reflection at the Rayleigh angle of water-alpha quartz boundary. The double Schoch shift collapses into one where the azimuthal directions are parallel to the plane of anisotropic symmetry.本实验针对水与z切向α石英（alpha quartz）的界面，开展了宽方位角与入射角范围内的声反射波场测量。该独有数据集采集自阿尔伯塔大学实验地球物理小组，实验系统采用谐振频率为0.7 MHz的大型发射换能器与高精度接收换能器，时间采样间隔为10ns，入射角采样步长为0.25°，方位角采样步长为10°。实测声反射率结果表明，水-α石英界面在瑞利角处存在双肖氏位移（Schoch shift）与零反射现象；当方位角方向平行于各向异性对称平面时，该双肖氏位移会合并为单一位移。