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Abstract:
Mount Cameroon is an active volcano located at the junction of the continental and oceanic part of the Cameroon Volcanic Line and has so far experienced effusive, explosive and hydromagmatic type eruptions. During the last century, it experienced 7 major volcanic eruptions, including the March-April 1999 eruption. Interring in its premonitory phase, it released a series of precursor earthquakes, one of which occurred on March 28 at 8:12 PM with a moment magnitude of only 5.1. Against all odds, this earthquake caused very significant damage in certain buildings in Buea, a city located at the foot of the volcano. The fact that a building by its typology and the nature of its materials has a natural frequency which when it is on a ground vibrating at equal frequency will get into resonance, bring us to think that it is possible to face here a phenomenon of site effects. In this work, we bring a beginning of explanations to this unequal distribution of the damage observed in the buildings of the city of Buea. Using the ambient noise recordings carried out between January 2005 and February 2007 by the stations of the project ‘’Cameroon Broadband Seismic Experiment’’ in the area of Mount Cameroon and its surroundings we proceeded to the computation of the horizontal to vertical spectra ratio. This reveals that seismic waves are amplified at some specific frequencies.Keywords: Mount Cameroon, site effects, HVSR, ambient noise and seismic waves.
