SEGJ Technical Conference

Velocity semblance analysis for GPR profile measurement - The near surface geophysical survey at Oyunuma in the Goshougake geothermal area, northeast of Japan-

Abstract The reflection records in GPR survey obtained in time scale. In order to discuss the target structure in depth scale, it is necessarily to derive the exact velocity of the EM (electromagnetic) waves. We developed computer program of the EM velocity analysis which can be applicable to the profiling survey in GPR using Visual studio 2015 C#. This newly developed tool is based on the velocity spectrum method which evaluates the most appropriate mean velocity semblance value. We applied the new method to the GPR data obtained at Oyunuma in Goshougake geothermal area and the EM velocity was estimated to be 0.093-0.14 m/ns. Using the EM velocity by the velocity analysis, the clear reflections revealed in the depth of 4-5 m from the surface of the sidewalk. The GPR reflections can be interpreted to be the ceiling of conduits of thermal water by comparison with the resistivity structure by ERT.