Karstens, Jens , Berndt, Christian and Crutchley, Gareth (2013) Why every dimension matters: Interpretation of volcanic landslide deposits from 3D seismic and time-lapse bathymetric data from offshore Montserrat. [Poster] In: 6. International Symposium on Submarine Mass Movements and Their Consequences. , 23.-25.09.2013, Kiel, Germany .

Abstract

The Soufrière Hills volcano on Montserrat has become one of the closest monitored island arc volcanoes since the onset of the ongoing (1995 - present) eruptive phase, which is characterized by the growth and collapse of andesite lava domes resulting in voluminous pyroclastic flows. In 2010 we acquired the first three-dimensional (3D) seismic dataset covering the submarine deposits of these recent pyroclastic flows, which overlie the remnants of much larger debris avalanches. The 3D seismic data allow a detailed reconstruction of changes in emplacement direction and the concurrent trigger of secondary failure of large amounts of seafloor sediment during the emplacement of a debris avalanche. We show how 3D seismic attributes add important information regarding the internal structure of landslide deposits and the tectonic framework. In combination with repeated bathymetric surveys covering the island’s shelf during the progressing emplacement of submarine pyroclastic flows, we are able to show that the pyroclastic deposits from distinct volcanic events are still well preserved and there is no significant basal erosion during the emplacement of submarine pyroclastic deposits on volcanic substrate. The cumulative deposition of pyroclastic deposits accounts for a significant part of the volcanic edifice.

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