Available online at www.scholarsresearchlibrary.com Scholars Research Library Archives of Physics Research, 2010, 1 (2):58-71 (http://scholarsresearchlibrary.com/archive.html) ISSN 0976-0970 58 Scholar Research Library Determination of elastic properties of the overburden materials in parts of Akamkpa, southeastern Nigeria using seismic refraction studies George, N. J. 1 , Akpan, A.E. 2 , George, A. M. 3 , Obot, I. B * . 4 1 Department of Science Technology, Akwa Ibom State Polytechnic, Ikot Osurua, Ikot Ekpene, Nigeria 2,3 Department of Physics University of Calabar, Calabar, Southern Nigeria 4 Department of Chemistry, University of Uyo, Nigeria ______________________________________________________________________________ Abstract Seismic refraction study was used to determine the depth, thickness and elastic properties of parts of Oban massif basement complex in Akamkpa which lies between latitude 5 0 00’-5 0 50’N and longitude 8 0 00’-8 0 50’E in Cross River State, Southern Nigeria. This was done using a twelve – channel signal enhancement seismograph, geophones, sledge hammer and metal plate. The P- wave and S-wave velocities were obtained from the arrival travel time read from velocity data. With the aid of standard velocity values for various rocks and the mathematical relationship of the measured and unknown parameters, the lithology, depth, thickness and elastic properties of the basement rocks were deciphered using V P /V S ratios and the associated calculated Poisson’s ratios. Keywords: elastic properties, basement, seismic refraction, V P /V S ratio and Akamkpa. ______________________________________________________________________________ INTRODUCTION It is quite not inconclusive to say that the variation of the ratio of compressional and shear wave velocities (V P/ V S ) is very much significant in the determination of the site for quarrying activities and engineering foundations since velocity varies withe densities and elastic moduli The elastic properties and the depth to different layers as well as the thickness of the layers can be determined from the knowledge of compressional and shear wave velocities [1]. The presence of gas in sedimentary rocks reduces the elastic moduli, Poisson’s ratio and the V P/ V S ratio [2].V P/ V S ratio greater than 2.0 are diagnostic of unconsolidated sand, while values less than 2.0 may indicate either consolidated sandstone or a gas- filled unconsolidated sand. The potential value of