Abstract

Subsurface soil varies from place to place due to the rock type, its mineral constituents, the climate of the area, time and other geological activities such as meteorite impact. The process that leads to the formation of impact crater can cause great variation in the subsurface soil characteristics, which may have an effect on civil engineering structures. Hence, the need to evaluate the subsurface soil of the impacted area. In this study, Seismic refraction and borehole data were used to achieve the aim. The result revealed that the overburden layer inside the crater is dominated by low-velocity values (< 750 m/s) which correspond with low N-values. Moderate seismic velocity values (750 – 1400 m/s) with moderate to high N-values were predominant for overburden soil within the crater rim and outside the crater. Slightly, moderately and highly weathered granite was observed at all survey lines with velocity values ranging from 1200 - 3450 m/s. The low N-values with low-velocity values obtained inside the crater are indications that the subsurface soil inside the impact crater area has been deformed and weakened as evident by the presence of brecciation which occurred during the impact process.