Sector collapse kinematics and tsunami implications (SEKT)

• Applicants: Professorin Dr. Katrin Huhn-Frehers; Professor Dr. Sebastian Krastel
• Subject Area: Geophysics ; Palaeontology
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 453685300

Sector collapses are a geological processes that affect most volcanic islands worldwide. These collapses can generate extremely large landslides and associated tsunamis, endangering coastal communities and seafloor installations. Major aim of this project is to gain deeper insight into the interplay between different collapse parameters (volume, source location, transport distance) and emplacement processes (timing, kinematics and dynamics) to enable a better determination of the tsunami magnitude and hence a better tsunami hazard assessment. New data collected during the Meteor cruise M154 offshore the volcanic island of Montserrat form the base of this project. The PIs KH and SK and the co-applicant CB were co-proponents of the expedition M154. During this expedition, the most recent landslides offshore Montserrat - Deposits 1 & 2 - were mapped. Particularly Deposit 2 is of great scientific interest as it seems to comprise two parts (Deposits 2a and 2b) separated by laterally extensive seismic reflectors. Furthermore, the emplacement of Deposit 2 seems to have triggered large-scale failure of sea floor sediment. A better understanding of the kinematics and the emplacement process of Deposit 2 has already been the aim of the IODP Leg 340 which drilled four sites along the slid masses of Deposits 1 and 2. Unfortunately, the core recovery in the slid masses of Deposit 2 itself particularly at the transition from Deposit 2a to 2b was negligible and, hence, many research questions remained unanswered. The new M154 data on which this proposal is based, especially 3D P-cable seismic and additional 2D seismic lines with significantly improved quality compared to older lines, and long sediment cores and comprehensive logging data utilizing gravity coring and MeBo70 drilling enable a better understanding of the collapse kinematics and the emplacement processes which provides a unique opportunity to parameterize landslide and tsunami models as key to a better tsunami hazard assessment. For this work we propose here two PhD projects which will complement each other according to the methods used. One PhD candidate (A) will mainly work on processing and interpretation of the 3D P-cable and 2D seismic as well as on core-log-seismic integration of the data. The second PhD (B) will focus on the gravity cores and the MeBo70 cores, in particular their sedimentological, geotechnical and compositional analyses. While core analyses will provide detailed information at individual core locations (e.g. stratigraphic ages, sediment composition, source area, degree of deformation, transport distance and initiation etc.), borehole logging and seismic data are used to interpolate these over the entire region. Through this multi-disciplinary approach, we will derive a comprehensive picture of the volcanic history of Montserrat as well as the interplay between flank collapses and associated landslide events and their emplacement processes.

• DFG Programme: Research Grants
• Co-Investigator: Professor Dr. Christian Berndt