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Western Earth Surface Processes Team


Geologic Framework of the Santa Barbara Coastal Plain

Location map of the Santa Barbara Coastal Plain. Location map of the Santa Barbara Coastal Plain.



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The geology of the Santa Barbara coastal plain is dominated by variably deformed Cretaceous through late Cenozoic marine and nonmarine sedimentary strata. These strata record a long history of continental-margin sedimentation, and deposits as young as Quaternary have sustained strong deformations that include folding, thrust and reverse faulting, and rotations of crustal blocks about steep axes. Quaternary deformation in this area has produced a series of uplifted and folded coastal terraces and alluvial fans that form a substrate for the rapidly growing Santa Barbara-Goleta urban corridor.

For more information on the geology of the Santa Barbara coastal plain see:

Minor, Scott A., Kellogg, Karl S., Stanley, Richard G., Stone, Paul, Powell, II, Charles L., Gurrola, Larry D., Selting, Amy J., and Brandt, Theodore R., 2002, Preliminary Geologic Map of the Santa Barbara Coastal Plain Area, Santa Barbara County, California: U.S. Geological Survey Open-File Report 02-0136 <http://pubs.usgs.gov/of/2002/ofr-02-0136/>.

Click here to see additional geologic maps and information on the region.
Map showing potential seismic sources of the onshore Santa Barbara fold and fault belt
Figure 2. Potential seismic sources of the onshore Santa Barbara fold and fault belt (SBFFB) showing south-dipping reverse faults, some of which are blind, with associated north-verging hanging-wall anticlines and footwall synclines. The Mission Ridge fault system is subdivided into the More Ranch (MrR), Mission Ridge (MsR), and Arroyo Parida segments. Additional onshore reverse faults include the Dos Pueblos (DP), Carneros (CF), San Jose (SJ), San Pedro (SP), Lavigia (LF), Mesa (MF), Santa Barbara Cemetery (SBC), Ortega Hill (OH), and Loon Point (LP) faults. Figure modified from Keller and Gurrola (2000).

The Santa Barbara coastal plain is transected by numerous active and potentially active folds and partly blind reverse faults of the Santa Barbara fold and fault belt (Fig. 2). Strong earthquakes that occurred in the region in 1925 (M 6.8) and 1978 (M 5.1) are evidence that such structures pose a significant earthquake hazard to the 200,000 people living on the coastal plain. Young landslide deposits along the steep lower flank of the Santa Ynez Mountains indicate that slope failures and mass movements have, and may continue to, threaten urbanized parts of the coastal plain. In addition, the coastal plain is subjected to limited groundwater resources and poor water quality due to salt-water contamination.

Submarine landslides have also been recognized offshore in the Santa Barbara Channel and are considered a potential source of local tsunami activity along the Santa Barbara coast.

Submarine multibeam image showing the Goleta landslide complex in the Santa Barbara Channel relative to the Santa Barbara coastal plain region
Submarine multibeam image showing the Goleta landslide complex in the Santa Barbara Channel relative to the Santa Barbara coastal plain region. Image source: Fisher, M. A., Normark, W. R., Greene, H. G., Lee, H. J., and Sliter, R. W., 2005, Geology and tsunamigenic potential of submarine landslides in Santa Barbara Channel, southern California: Marine Geology, v. 224; doi 10.1016/j.margeo.2005.07.012, no. 1-4, p. 1-22.

See additional information about the Transverse Ranges Region:

Geology of the Inland Empire (includes information about the San Andreas Fault and other fault systems)
San Gabriel Mountains
San Gorgorio Pass Region

San Bernardino Mountains

Return to the Geology of the Transverse Ranges