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| | Abstract | | We conducted 2-dimensional linear array microtremor surveys (2D-LAMS) at PWRI in Tsukuba, and discussed the determined phase velocity differences between two measurement lines crossing perpendicularly each other. 2D-LAMS is one of the effective methods to investigate 2-dimensional underground S-wave velocity structure. Generally, in the SPAC method, azimuthal average of coherency is needed to calculate. But if waves come from various directions evenly, the calculation can be omitted. In other words, if there is a deviation in the direction, this method requires some additional processing to determine correct phase velocities. In this study, we conducted field experiments to investigate the differences in phase velocities of two measurement line directions, and calculated the wave propagating directions. As the result, there is a deviation in the wave propagating directions observed by 2D-LAMS, and the dispersion curves obtained by different directions may be affected by the wave propagating directions. |
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