HR: 1340h
AN: V33B-1386    [Abstracts]
TI: Rayleigh Wave Phase Velocity Structure of the Cameroon Volcanic Line Region
AU: Shore, P
EM: patrick@seismo.wustl.edu
AF: Washington University in St. Louis, Department of Earth and Planetary Sciences Campus Box 1169, EPSc Room 110 1 Brookings Drive, St. Louis, MO 63130-4899, United States
AU: * Euler, G G
EM: ggeuler@seismo.wustl.edu
AF: Washington University in St. Louis, Department of Earth and Planetary Sciences Campus Box 1169, EPSc Room 110 1 Brookings Drive, St. Louis, MO 63130-4899, United States
AU: Tibi, R
EM: tibi@mantle.wustl.edu
AF: Washington University in St. Louis, Department of Earth and Planetary Sciences Campus Box 1169, EPSc Room 110 1 Brookings Drive, St. Louis, MO 63130-4899, United States
AU: Wiens, D A
EM: doug@wustl.edu
AF: Washington University in St. Louis, Department of Earth and Planetary Sciences Campus Box 1169, EPSc Room 110 1 Brookings Drive, St. Louis, MO 63130-4899, United States
AU: Larson, A M
EM: alarson@geosc.psu.edu
AF: Pennsylvania State University, Department of Geosciences 446 Deike Building, University Park, PA 16802, United States
AU: Nyblade, A
EM: andy@geosc.psu.edu
AF: Pennsylvania State University, Department of Geosciences 446 Deike Building, University Park, PA 16802, United States
AU: Tokam, A P
EM: atokam@uycdc.uninet.cm
AF: University of Yaounde I, Department of Physics Faculty of Science P.O. Box 812, Yaounde, 00000, Cameroon
AU: Tabod, C
EM: ctabod@uycdc.uninet.cm
AF: University of Yaounde I, Department of Physics Faculty of Science P.O. Box 812, Yaounde, 00000, Cameroon
AU: Nnange, J M
EM: mbollefr@yahoo.fr
AF: The Institute for Geological and Mining Research (IRGM), P.O. Box 4110, Yaounde, 00000, Cameroon
AU: Ateba, B
EM: atebs@yahoo.com
AF: The Institute for Geological and Mining Research (IRGM), P.O. Box 4110, Yaounde, 00000, Cameroon
AB: The Cameroon Volcanic Line (CVL) is an 1800 km lineament of Cenozoic volcanism that extends from the Gulf of Guinea into Central Africa. With most of the line having experienced recent holocene volcanism, the CVL is one of the more prominent volcanic tracks exhibiting little to no discernible age progression. Previous interpretations of the CVL have been diverse and included volcanic activity associated with laterally transported material from a plume, multiple plumes, rift-flank processes, plate-driven Richter rolls, plume-fed small-scale convection cells, or propagating lithosphere cracks in order to reconcile the lack of age progression with the strong linearity and position of the CVL. Discriminating between these models can be significantly aided by the determination of the extent and depth of the source of the volcanism. In early 2005, a dense broadband seismometer array located over the continental section of the CVL was deployed to image the underlying mantle structure and resolve the source of the volcanism. This two-year PASSCAL deployment consisted of 8 trial stations for the first year and the following year was upgraded to 32 stations with a station spacing of 50 to 200 km. We present preliminary results of surface wave phase velocity maps from this new dataset that successfully image a low-velocity anomaly beneath the CVL as well as high velocities associated with the lithosphere of the Congo Craton. Phase velocity maps were determined by an inversion of teleseismic Rayleigh waves with Forsyth and Lee's two-plane wave method to reduce bias from multipathing. The low-velocity anomaly is observed over a period range of 20 to 140 s suggesting that the CVL anomaly extends across a substantial depth range of the lithosphere and asthenosphere. Furthermore, the lowest velocities of the anomaly are centered at the junction of the 'Y' in the volcanic track, 400 km northeast (inland) of the CVL's largest active volcano Mt. Cameroon.
DE: 7208 Mantle (1212, 1213, 8124)
DE: 7218 Lithosphere (1236)
DE: 7255 Surface waves and free oscillations
DE: 7270 Tomography (6982, 8180)
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting