SPECTRAL CHARACTERISTICS AND SOURCE PARAMETERS OF MICROEARTHQUAKES FROM THE MT CAMEROON VOLCANIC REGION, WEST-AFRICA

Estimates of source parameters (seismic moment, source radius and stress drop) for a representative sample of 33 Mt Cameroon region microearthquakes, with magnitudes in the range M(D) = 0.8-2.8, have been obtained from the analysis of their far-field displacement amplitude spectra. The spectral character of these events seems to be characterized by a lack of high frequencies. The computed seismic moments lie between 10(11) and 10(16) N m and vary linearly with magnitude, albeit with some scatter. Source radii are relatively large, in the range 135-703 m. The stress drops are small (0.4-19 bar) and roughly constant, independent of seismic moment, thus suggesting that the property of self-similarity seems to hold over this moment range for this area.