Potential for tsunami generation along the western Great Bahama Bank by submarine slope failures
Presented by Jara S. D. SCHNYDER on 23 Sep 2013 from 17:15 to 19:15
Type: Poster presentation
Session: Poster session
Multibeam and seismic data reveal repeated slope failures at various scales along the western slope of Great Bahama Bank. In addition, creeping and incipient slump scars indicate slope instabilities that will lead to large-scale slope failures in the near future. To assess the potential of tsunami generation by these mass movements several tsunami scenarios have been constructed and simulated numerically for the Straits of Florida. They are based on the estimated volume and nature of a potential landslide, and failure scenarios of the known scars and mass transport complexes (MTC). During the 2010 Carambar cruise four connected scars with widths of 2.0, 2.2, 3.7 and 1.6 km and lengths of 3.0, 1.4, 3.2 and 3.0 km, respectively, were identified. Three tsunami scenarios have been chosen and simulated for the Straits of Florida. The first scenario, Single Slope Failure (SSF), assumes a failure mass volume of 1.18 km3, which corresponds to the largest of the three failure scars. For the second setup, Combined Slope Failure (CSF), we add the extent of the failure scars together (9 km) and assume that the landslides were sliding in a single event. The failure volume was estimated to be 3.42 km3. For the third Major Slope Failure scenario (MSF), a scar length of 80 km, observed south of the MTC, and failure volume of 24 km3 is used. The numerical model is based on the non-hydrostatic wave model NHWAVE developed at the Center for Applied Coastal Research at the University of Delaware. Results show that for the first Scenario within one minute after the failure event a wave height up to 1 m is generated. For the second Scenario initial wave heights up to 2 m can be expected. A catastrophic release, such as the third Scenario assumes, would generate an initial tsunami wave height of 2.5 m, with a possible major impact on both sides of the Straits. The waves propagate across the Straits of Florida, impacting on the coastline only 15 min after their initial release. Three different terminal velocities for the failure masses were used for the simulations; i.e. 20 m/s, 50 m/s and 100 m/s. Initial wave heights strongly depend on terminal velocity and duration of the landslide. A massive slope failure, such as MSF, with a terminal velocity of 50 m/s and a duration of 2 min could release a wave up to 5.5 m height. The modeling demonstrates that the generation of tsunamis by slope failure in a tectonically inactive area can cause a potential hazard in the densely populated urban areas of south Florida and the Keys.
Location: GEOMAR East shore
Address: Wischhofstr. 1-3 / D-24148 Kiel