SEISMIC REFRACTION SURVEY TO EVALUATE ROCK DEPOSIT FOR QUARRYING: A CASE STUDY

Journal Vol.: Volume 9 Author(s): SETH OWUSU NYAKO, E. B. FREMPONG Address(es): Research Scientist, Building and Road Research Institute, Council for Scientific and Industrial Research, Ghana Abstract: A seismic refraction survey was carried out over granite exposure at Sahoma a village near Bibiani in the Western Region of Ghana. A total length of 990m traverse lines was covered over the entire exposure. The data was interpreted by travel - time curves to yield the seismic velocity of the various underlying formations and their respective depth of occurrence. The velocities were then correlated with a table of calculated seismic velocities of the identifiable rock types found at the site to determine the competence of the materials for road construction. The interpreted results indicated that, the bulk of the material found at the site had velocities less than 2500m/sec. The highest velocity of 5000m/sec associated with the bedrock was recorded as a single point anomaly and occurred at the depth of 19.55m from the ground surface. An average depth of 17m is expected to penetrate hard formations, however an optimum depth of 25m to bedrock is estimated over the prospect. Drilling on top of the anomalies could determine uniquely the depth extent, provide samples for analysis as well as establish the viability of the prospect.