Marine Geophysics and Hydroacoustics

Sector collapse kinematics and tsunami implications -SEKT

Summary - M154/1 April 3rd to April 25th, 2019 Mindelo (Cape Verde) - Point-á-Pitre (Guadeloupe)

Deep-seated  collapses  of  volcanic  islands  have  generated  the  largest  volume  mass  flows worldwide. These mass flows might trigger mega-tsunamis. The way in which these collapse events are emplaced is poorly understood, even though this emplacement process determines the scale of associated tsunamis. Key questions such as whether they are emplaced in single or multiple events, how they may incorporate  seafloor  sediment  to  increase  their  volume,  and  how  they  are  related  to  volcanic eruption cycles and migration of volcanic centers, remain to be answered. More The  main  scientific  goals  of  this  project  /  cruise  are  to  determine  where  the  landslides  are sourced from; to understand how these landslides are emplaced; and to understand the relationship between landslides, eruption cycles and initiation of new volcanic centres. The most crucial task during the cruise was the collection of a high-resolution 3D seismic cube – using the P-Cable seismic system –extending the cube collected in 2010 out beyond the edge of debris avalanche deposit. With this cube, it is possible a) to determine whether the crucial Deposit 2 consists  of  two  events  or  if  it  was  caused  by  one  event  that  changes  character  laterally,  b)  to determine the amount of erosion at the slide plane; and c) to determine the geometry at the toe of the deposit. This will be achieved by creating horizon attributes (steering, dip, amplitude, RMS amplitude)  and  volume  attributes  (co-herency,  similarity,  etc.) of the 3D seismic data and integrating them via core-log seismic integration with the results of the two IODP cores within the planned cube and with the information from MeBo drilling during the second leg of the cruise. In order to provide velocity information for the 3D processing after the cruise, we acquired four ocean bottom seismometer (OBS) data sets distributed within the area of the P-Cable cube. The ocean bottom  seismometers  were  deployed  before  the  3D  data  acquisition  commenced,  and  were recovered after shooting had stopped.















Participants (Dennis Kunde, Henriette Wilckens, and Arne Lohrberg) of on deck of Meteor in April 2019 in front of Mt. Monserrat.