NEHRP Clearinghouse
- Title
- Cruise Report for 01-99-SC Southern California Earthquake Hazards Project.
- File
- PB2006108452.pdf
- Author(s)
- Normark, W. R.; Reid, J. A.; Sliter, R. W.; Holton, D.; Gutmacher, C. E.
- Source
- January 1999, 60 p.
- Identifying Number(s)
- USGS-OFR-99-560
- Abstract
- The primary objective of the project is to help mitigate the earthquake hazards for the Southern California region by improving our understanding of how deformation is distributed (spatially and temporally) in the offshore with respect to the onshore region. To meet this objective, we are conducting field investigations to observe the distribution, character, and relative intensity of active (i.e., primarily Holocene) deformation within the basins and along the shelf adjacent to the most highly populated areas. In addition, acoustic imaging should help determine the subsurface dimensions of the faults and identify the size and frequency of submarine landslides, both of which are necessary for evaluating the potential for generating destructive tsunamis in the southern California offshore. In order to evaluate the strain associated with the offshore structures, the initial results from the field mapping under this project will be used to identify possible sites for deployment of acoustic geodetic instruments to monitor strain in the offshore region. A major goal of mapping under this project is to provide detailed geologic and geophysical information in GIS data bases that build on the earlier studies and use the new data to precisely locate active faults and to map recent submarine landslide deposits. The priorities for the field-mapping program under this hazards project are keyed to those areas with the greatest potential for impact on the Southern California populace: (1) the coastal strip (coastal zone and continental shelf) between Los Angeles and San Diego, where much of the hazard appears to be associated with strike-slip or obliqueslip faults; (2) active faults within the Santa Monica, San Pedro, and San Diego Trough basins, where more extensive sedimentation has left a greater stratigraphic record; (3) the offshore extension into the Santa Barbara Basin of the fold and thrust belt of the adjacent Western Transverse Range; (4) the boundary (Channel Islands region) between the inner California Borderland (strike-slip dominated deformation) and the Santa Barbara Channel (thrust and fold deformation).
- Keywords
- ; Geologic faults; Deformation; California; Mitigation; Acoustic imaging; Hazards; USGS; Cruises; Offshore; Natural hazards; Earthquakes