Thickness Variations in the Lithospheric Mantle and the Low Velocity Zone of the Adamawa Plateau (Cameroon) from Teleseismic Receiver Functions

Abstract

Teleseismic events recorded by stations located in the Adamawa Plateau have been treated using the inversion method of receiver functions. These six stations are part of a network of 32 large strip seismic stations installed in Cameroon between 2005 and 2007. This method allowed us to investigate the lithospheric mantle in that region. The results obtained from the velocity model have been compared to some existing results in this region. These results show the existence of a thick crust having an average thickness of about 35.2 km and a corresponding S wave velocity of 3.7 km/s. For an average S wave velocity of 4.4 km/s the lithospheric mantle appears to be thin in nature and has a thickness that varies from 39 km and 49.6 km. Beyond the lower lithospheric mantle, there exists a low velocity zone, whose thickness varies between 20 km and 43.9 km. The variation of the low velocity zone leads to variation of the lower boundary of the lithospheric mantle boundary at the depths ranging from 73.8 km and 85 km.

Depth Variation of the Lithosphere beneath Garoua Rift Region (Cameroon Volcanic Line) Studied from Teleseismic P-Waves

“…In the study area, two stations (red color) were installed in 2005 January and operated during 2 years; the remaining four stations (yellow color) operated only during the second year of the experiment. The station spacing during the second year (2006) of operation was about 50 to 150 km [26]. From the earthquake data recorded, the teleseismic events that occurred at epicentral distances between 30˚…”

“…The circled numbers refer to station codes, for example, 28 refers to station CM28 and the blue rectangle represents the study area (Modified after [22]). To complete the estimation of the receiver functions, the recovery percentage of the original radial waveform was evaluated from the rms misfit between the original radial waveform and the convolution of the radial receiver function with the original vertical component [26]. Events that were recovered to less than 85 percent were rejected.…”