Large, deepwater slope failures; implications for landslide-generated tsunamis
Large, deepwater slope failures; implications for landslide-generated tsunamis
Geology (Boulder) (August 2012) 40 (10): 931-934
- acoustical methods
- active margins
- Atlantic Ocean
- bathymetry
- bottom features
- continental margin
- data processing
- deep-water environment
- digital simulation
- earthquakes
- echo sounding
- Europe
- failures
- geologic hazards
- geophysical methods
- geophysical surveys
- Gorringe Bank
- Iberian Peninsula
- marine environment
- mass movements
- multibeam methods
- natural hazards
- North Atlantic
- numerical models
- ocean floors
- risk assessment
- slope environment
- slumping
- Southern Europe
- surveys
- three-dimensional models
- tsunamis
Deepwater landslides are often underestimated as potential tsunami triggers. The North Gorringe avalanche (NGA) is a large ( approximately 80 km (super 3) and 35 km runout) newly discovered and deepwater (2900 m to 5100 m depth) mass failure located at the northern flank of Gorringe Bank on the southwest Iberian margin. Steep slopes and pervasive fracturing are suggested as the main preconditioning factors for the NGA, while an earthquake is the most likely trigger mechanism. Near-field tsunami simulations show that a mass failure similar to the NGA could generate a wave >15 m high that would hit the south Portuguese coasts in approximately 30 min. This suggests that deepwater landslides require more attention in geo-hazard assessment models of southern Europe, as well as, at a global scale, in seismically active margins.
