This study was carried out in Harat Rahat (south of
Almadinah Almonwarah) using seismic reflection and resistivity methods. The
main objectives of this study are to determine the extent of the basaltic layer
and to define the subsurface faults and fractures that could affect and control
the groundwater movement in the study area. A 2D seismic profile was acquired
and the result shows that the subsurface in the study area has a major fault.
We obtained a well match when the seismic result was compared with drilled
wells. As a complementary tool, the resistivity method was applied in order to
detect the groundwater level. The results of the resistivity method showed that
six distinct layers have been identified. The interpretation of these six
layers show that the first three layers, the fourth layer, the fifth layer and
the bottom of the section indicated various subsurface structures and
lithologies; various basaltic layers, fractured basalt, weathered basement and
fresh basaltic layers, respectively. It is obvious that the eventual success of
geophysical surveys depend on the combination with other subsurface data
sources in order to produce accurate maps.