Determination of depth to bedrock in Afikpo syncline of the Benue Trough, Nigeria, using seismic refraction methods.

Abstract

A three channel digital signal enhancement Seismograph model S79-3, was used in continuous profiling to determine the depth to bedrock in Afikpo syncline. Afikpo syncline came as a result of instability of accumulated sediments in the Benue trough during the Albian-Turonian tectonic episode. Incessant collapse of building structures in Nigeria compelled us to carry out
seismic refraction surreys in the fast developing Ndibe beach. The results of the survey gave a two-layer model. The seismic P-wave velocity of the weak overburden sediment varies from
277-512ms while layer two has a P-wave velocity which ranges from 370-1408ms. The depth to bedrock varies from 2.0 to 3.98m. The depth to the expected Afikpo sandstone in the Ndibe
beach area in 3.98m and any engineering structure placed in the Afikpo sandstone will be geotechnical sound. The seismic refraction method has proved to be an indispensable tool
used to determine the depth to bedrock.
Key Words: Bedrock, Seismic Refraction, Velocity, Geology