Trans-Terrestrial Landslides and the Impact on the Marine Environment: Big Sur Coastline, California

Recent investigation of the continental margin south of Point Sur, along the coastal area of the central Santa Lucia Mountain Range, using EM300 30 kHz multibeam bathymetry, Klein 100 kHz side-scan sonar, and 3.5 kHz seismic reflection profile data indicate that extensive landslide deposits exist along the distal part of the continental shelf and upper slope. Submersible dives using the Delta revealed that the deposits imaged in the remotely sensed data sets were composed of angular to sub-rounded boulders, cobbles and pebbles lying at a depth of 80 to 130m with very little biological growth and sediment cover suggesting a fairly young (~100 years) age for the deposits. Based on preliminary aerial examination of the deposit we estimate a volume of 1 km³ that came to rest 2 km offshore of the Big Sur coastline. If such a deposit were to fail at one time it could produce a significant tsunami. We will present evidence that shows the distribution of the slide and a model of the possible impact wave that it could have generated.