Incorporating Geologic Constraints Into a Tsunami Hazard Assessment, South-Central Coastal California
Abstract
The central California coast lies within a tectonically active region where displacements of the sea floor from both tectonic fault ruptures and submarine landslides may pose a tsunami hazard. The Pacific Gas and Electric Company recently conducted an extensive reanalysis of marine data along the continental margin from Point Conception to Point Sur (34.5° to 36.5°N) to identify potential tsunami sources. The study area encompasses the continental shelf and slope, including the offshore Santa Maria basin, Sur basin, the western part of the Ventura basin, the Santa Lucia Bank, the Santa Lucia basin, and the Santa Lucia Escarpment. The primary objectives of this study were to: a) perform a comprehensive compilation and review of available marine geophysical data; b) construct digital elevation models (DEMs) at the highest possible resolution by re- processing individual surveys that comprise the NGDC/NOAA coastal relief model; c) use these combined data sets in a GIS environment to aid in the identification and characterization of local tsunami sources and to provide a reference sea floor surface to be used in modeling tsunami effects; and d) develop a probablisitic framework to evaluate hazard from both far-field and near-field tsunami sources. A geomorphic seafloor classification map was developed based on the DEMs, published maps, available single channel seismic reflection and multibeam bathymetric data, as well as known/inferred relationships between landforms, modes of sediment transport and erosion, and underlying geologic structure. Estimates of the recurrence and maximum dimensions of large landslides along the Santa Lucia Escarpment are based on interpretation of the number, extent, and depth of burial by pelagic sediments of individual slide masses. Fault source and potential slope failure parameters were then used in a variable-grid, non-linear tsunami wave propagation model to assess the impact of these potential tsunami sources on the central California coast.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2006
- Bibcode:
- 2006AGUFMOS34C..02H
- Keywords:
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- 3022 Marine sediments: processes and transport;
- 3045 Seafloor morphology;
- geology;
- and geophysics;
- 3075 Submarine tectonics and volcanism;
- 9350 North America