Contrasts in morphology and deformation offshore Montserrat: New insights from the SEA-CALIPSO marine cruise data

During the December 2007, SEA-CALIPSO experiment we collected seismic reflection profiles offshore of Montserrat. Off the east coast, we imaged deep fans of volcaniclastic debris from three volcanoes progressively active from similar to 2 Ma to present. Near-shelf sedimentation rates of 8-9 cm/ka are approximated following cessation of local volcanic activity. The fans were deposited on sediments with apparent dips towards the ESE-trending Montserrat-Havers fault system (MHFS) in southern Montserrat. The MHFS encloses the Soufriere Hills Volcano, has elevated crustal blocks at Roche's Bluff, St. Georges Hill, and Garibaldi Hill, and extends off the west coast. Off the west coast, the N-dip of two faults supports a N-dip interpretation for a major component of MHFS, the Belham Valley fault. We propose that local deformation is affected by stress redistributions consistent with a right-stepping, sinistral en-echelon fault system, but the interplay of transtension and magmatism has resulted in complex and evolving stress regimes. Citation: Kenedi, C. L., R. S. J. Sparks, P. Malin, B. Voight, S. Dean, T. Minshull, M. Paulatto, C. Peirce, and E. Shalev (2010), Contrasts in morphology and deformation offshore Montserrat: New insights from the SEA-CALIPSO marine cruise data, Geophys. Res. Lett., 37, L00E25, doi:10.1029/2010GL043925.