RESEARCH ARTICLE The structure and morphology of the Basse Terre Island, Lesser Antilles volcanic arc Lucie Mathieu & Benjamin van Wyk de Vries & Claire Mannessiez & Nelly Mazzoni & Cécile Savry & Valentin R. Troll Received: 2 July 2012 / Accepted: 18 February 2013 / Published online: 5 March 2013 # Springer-Verlag Berlin Heidelberg 2013 Abstract Basse Terre Island is made up of a cluster of composite volcanoes that are part of the Lesser Antilles volcanic arc. The morphology of these volcanoes and the onshore continuation of the grabens and strike–slip faults that surround the island are poorly documented due to erosion and rainforest cover. Therefore, we conducted a morphological analysis of the island using Digital Elevation Model (DEM) data integrated with field observations to document erosional, constructional, and deformational pro- cesses. A DEM-based analysis of 1,249 lineaments and field structural measurements of 16 normal faults, 3,741 veins and fractures, and 46 dykes was also carried to document the structures that predominate in sub-surface rocks. The results indicate that the over 1-My-old and elongated Northern Chain volcano, which makes up the northern half of the island, was built by high eruption rates and/or a low viscos- ity magma injected along the N–S to NNW–SSE-striking extensional structures formed by the flexure of the litho- sphere by the overall subduction regime. After 1 Ma, the southern half of the island was shaped by an alignment of conical volcanoes, likely built by a more viscous magma type that was guided by the NW–SE-striking Montserrat- Bouillante strike–slip fault system. These N to NNW and NW structural directions are however poorly expressed on- shore, possibly due to slow slip motion. The sub-surface rocks mostly contain E–W-striking structures, which have likely guided the many flank instabilities documented in the studied area, and guide hydrothermal fluids and shallow magmatic intrusions. These structures are possibly part of the E–W-striking Marie-Gallante offshore graben. Keywords Volcano-tectonic . Structure . Morphology . Digital elevation model (DEM) . Basse Terre Island . Lesser Antilles Introduction Basse Terre Island is part of the Lesser Antilles volcanic arc (Fig. 1) and is made of a cluster of composite volcanoes that become progressively younger toward the south (Samper 2007; Samper et al. 2007). The island is surrounded and underlain by the Marie-Gallante and Bertrand-Flamouth gra- bens and by the Montserrat-Bouillante strike–slip fault zone (Feuillet 2000; Fig. 1a). The influence of these regional tec- tonic systems on the structure of the island is poorly under- stood. Overall, the structure of Basse Terre Island is not well documented due to intense weathering and rainforest cover, and has mostly been inferred from alignments of volcanic edifices and on the basis of a small number of recorded faults, Editorial responsibility: A. Gudmundsson Electronic supplementary material The online version of this article (doi:10.1007/s00445-013-0700-y) contains supplementary material, which is available to authorized users. L. Mathieu Department of Geology, Trinity College Dublin, Dublin, Ireland L. Mathieu : B. van Wyk de Vries : C. Mannessiez : N. Mazzoni : C. Savry Laboratoire de Magmas et Volcans, Université Blaise-Pascal, Clermont-Ferrand, France V. R. Troll Department of Earth Sciences, CEMPEG, Solid Earth Geology, Uppsala University, Uppsala, Sweden Present Address: L. Mathieu (*) CONSOREM, Université du Québec à Chicoutimi (UQAC), 555 boulevard de l’université, Chicoutimi, Québec G7H2B1, Canada e-mail: mathiel@tcd.ie Bull Volcanol (2013) 75:700 DOI 10.1007/s00445-013-0700-y