A method of estimating near‐surface velocity models with rugged topography using refraction travel‐time

Summary It is very difficult to obtain reasonable near-surface velocity models with rugged topography. Generally the conventional methods, such as a shallow refraction survey, up-hole survey and so on, do not work well themselves in areas with a rugged surface. The subsequent interpolation in building velocity models adds more to the unreliability of the so-built model. To solve this problem, we developed a new method for estimating near-surface velocity models with rugged topography using refraction travel-time based on the assumption of slow lateral near-surface velocity variation, and the assumption to the refractor is relaxed to two inclined flat ones. Since only the refraction travel times and the elevation differences between the corresponding sources and receivers are needed and the weathering layer velocity (LVL velocity) and interpolation are saved during obtaining near-surface velocities, more reliable nearsurface velocity models can be built with this method for areas with rugged topography. Application of this method to both synthetic data and real data has obtained satisfying