USING THE SLOPE OF THE OVERBURDEN AND THE SECOND SEGMENTS OF THE REFRACTED PATHS TO DETERMINE THE OVERBURDEN DEPTH (Z_O ) IN HORIZONTAL THREE LAYER CASE

The present study aims to determine the slope of the overburden and the second segments of the refracted paths to determine the overburden depth (zo ) in horizontal three-layer case. A signal, similar to a sound pulse, is transmitted into the Earth. The signal recorded at the surface can be used to infer subsurface properties. There are two main classes of the survey: Seismic Refraction: the signal returns to the surface by refraction at subsurface interfaces, and is recorded at distances much greater than the depth of investigation. Seismic Reflection: the seismic signal is reflected back to the surface at layer interfaces, and is recorded at distances less than the depth of investigation. Using the slope of the first (overburden) and the second (first refracted) segments in Fig. 2 the second refracted branch has a travel time of T=X/V2+Ti2 , the overburden depth (Z0) is computed by the second layer formula Z =Z0+Z1. The velocities and are determined from the slope of the T - X Plot; slope = 1/v0,1/v1 and 1/v2 respectively.