HR: 08:55h
AN: NG21A-04    [Abstracts]
TI: Size distribution of submarine landslides and implications for tsunami probability in Puerto Rico
AU: * ten Brink, U
EM: utenbrink@usgs.gov
AF: USGS, 384 Woods Hole Rd., Woods Hole, MA 02543 United States
AU: Geist, E L
EM: egeist@usgs.gov
AF: USGS, 345 Middlefield Rd., Menlo Park, CA 94025 United States
AB: Using detailed bathymetry along the northern edge of the carbonate platform north of Puerto Rico, we show that the size distribution of 160 interpreted submarine landslide volumes follows a power law relationship. The power law exponent of these landslides (0.5) is similar to those for rock falls on land (0.4-0.58), commensurate with their interpreted failure mode as rockslides and debris avalanches. The size distribution of submarine landslides >30 km³ appears to have an exponent of 1.4, similar to landslides on land formed by variable processes (1.2±0.3). The different distribution of the largest landslides may either reflect under sampling, or excavation below the carbonate layers into the underlying geotechnically-different metavolcanic rocks. The size-frequency distribution of submarine landslides <0.1 km³ deviates from a power law probably because of under sampling. We performed tsunami simulations to establish the minimum landslide volume (1.7 km³) that could cause a damaging tsunami (>2 m maximum runup) along the north shore of Puerto Rico. Tsunami propagation and runup was calculated using a non-linear, weakly dispersive shallow-water wave model with an approximate landslide velocity of 40 m/s. Coupling the size distribution of submarine landslides with these tsunami simulations and with knowledge of the time period over which they occurred, provides a method to estimate the average recurrence interval of landslide-generated tsunamis.
UR: http://woodshole.er.usgs.gov/project-pages/caribbean/index.html
DE: 1810 Debris flow and landslides
DE: 4219 Continental shelf and slope processes (3002)
DE: 4468 Probability distributions, heavy and fat-tailed (3265)
DE: 4564 Tsunamis and storm surges
SC: Nonlinear Geophysics [NG]
MN: Fall Meeting 2005