PURPOSE: To correctly evaluate the anisotropy of ground even at shallow ground by rotation-processing seismic wave record for every specific angle and calculating total energy for each rotation angle in the region surrounded by a window function.

CONSTITUTION: Excitation is made by hitting plates placed at two points apart 1.5m from a boring hole with a maul. A three-component (one vertical motion component, two horizontal motion components) receiver with an azimuth finder is fixed in the boring hole. After preprocessing the seismic wave signal received with in-hole receiver, a window function is determined by polarization process. For the seismic wave record for two horizontal motion components, rotation process is conducted at every 1 degree, the total energy in every rotation angle in a region surrounded by the window function, and the minimum of the total energy is obtained at each measuring depth. Whether the arrangement of the phase at each depth of the rotated and synthesized wave records is further improved than the present record, is checked. If it is not improved, this process is repeated.