Journal of Earth Sciences and Geotechnical Engineering

Imaging the Subsurface in the Cameroon Centre Region using the Audio-magnetotellurics (AMT) Soundings forthe Monitoring of the Monatele-sa’a Earthquake Area

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• Abstract

  In monitoring the Monatélé-Sa’a earthquake area, audiomagnetotelluric investigation was carried out using a scalar instrument with a frequency range from 4.1 Hz to 2300 Hz. Data have been collected in the Ntui-Sa’a area near Monatélé, along a profile containing seven (07) stations directed N-S, covering approximately a distance of 16.5 km. This profile crosses the Sanaga River which seems to be parallel to a buried big fault which shows no indication on the surface. The validation of the measured resistivity and calculated phase data set is done by the application of dimensionality. The interpretation of data using 2D inversion imaging of the subsurface has lead to the confirmation of two major discontinuities:

  •  The Sanaga fault oriented SSW-NNE, covered by a thick layer of alluvial deposit in the Elang III area. This fault is bisected to a lateral fracture between Nkolessono and Elang III.
  •  The fault network in Biakoa-Goura intersected the Sanaga fault is characterised by secondary faults in Biakoa and Talba.

  The presence of a fault network traversing the Sanaga fault shows that the study area belongs to the major tectonic accident area known as the Cameroon Central shear zone (CCSZ). The tectonic node relaxation of the Biakoa-Goura seems to be the origin of the February 2005 earthquake in Monatélé and Yaoundé northern areas.