Item

Abstract

The Cameroon Volcanic Line (CVL) hosts volcanoes within a complex tectonic framework. As part of the CVL, Bioko (Equatorial Guinea) is a volcanic island composed of three coalescing basaltic shield volcanoes (Pico Basilé, Pico Biaó and Gran Caldera de Luba) dotted with numerous scoria and cinder cones. The spatial distribution of these cones and their relationship to other volcano-tectonic structures have yet to be studied.We analyzed synthetic aperture radar data (TerraSAR-X/TanDEM-X) and mapped structural features such as faults, fractures, lineaments, and cone morphologies.We mapped 437 vents for 342 cones and 1337 lineaments. The vents are clustering along the major axis of Pico Basilé with a bimodal pattern trending N30° and N70°, and along the ridge between Pico Biaó and Gran Caldera de Luba trending N90°, indicating major rift zones. The NE-SW trends align with the CVL, and transform faults related to the opening of the Atlantic Ocean. On a regional scale, we hypothesize that the described trends are linked to strike slip tectonics as proposed for other volcanoes along the CVL. Furthermore, we found indicators for volcano-tectonic processes such as gravitational spreading and buttressing effects that modify the stress field locally. Based on our findings, we propose a new classification scheme for rift zones at complex / compound volcanic systems.