Unified Interior Regions

California

The Southwest Region includes California, Nevada, and Arizona. The Regional Office, headquartered in Sacramento, provides Center oversight and support, facilitates internal and external collaborations, and works to further USGS strategic science directions.

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A map shows the seafloor in a motif of dark and light areas.
December 31, 2014

Acoustic backscatter data

Acoustic backscatter data show the intensity of an acoustic pulse off the seafloor and back to a ship. Brighter tones indicate a strong intensity (possibly harder seafloor?), while darker ones indicate a weaker intensity (possibly softer seafloor?). Many seafloor physical parameters influence backscatter intensity but these data are helpful in determining the distribution

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Map illustration shows the seafloor surface in a 3-D fashion.
December 31, 2014

Shaded-relief bathymetry data

State-of-the-art multibeam and bathymetric sidescan sonar systems collect high-resolution bathymetry and acoustic backscatter data. These data are the foundation on which most groundtruthing and derivative products are based. Bathymetry data display the shape of the seafloor including rough terrain (possibly rock outcrops?), smooth terrain (possibly sedimented?), canyons,

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Computer-generated diagram from lidar data shows beach, amusement park, river, and cliff with houses in a stippled pattern.
December 31, 2014

Lidar point cloud with digital still image overlay

A digital still image can be overlaid onto the lidar “point cloud” data to give it a realistic 3D look.

A cross-section of earth's crust reveals the layered sediment and features of earthquake faults.
December 31, 2014

Seismic reflection profile

Example of a high-resolution seismic-reflection profile collected by the USGS offshore of Point Sal. The profile shows a cross-section of the earth's crust down to about 240 meters. The dashed red lines show the Hosgri Fault Zone, part of a strike-slip fault system that extends for about 400 kilometers along the California coast from Point Arguello to Bolinas. The thin

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A cross-section of earth's crust reveals the layered sediment and features of earthquake faults.
December 31, 2014

Seismic reflection profile

Example of a deep-penetration multichannel seismic-reflection profile collected offshore of San Mateo County, from the USGS National Archive of Marine Seismic Surveys (NAMSS). The profile shows a cross-section of the earth's crust from the surface down to a depth of about 3 kilometers. The layers show

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Tim Elfers watches the incoming waves while conducting a bathymetric survey of the nearshore in Santa Cruz, California.
December 31, 2014

Conducting Bathymetric Surveys

USGS scientist Tim Elfers conducts a bathymetric (depth) survey from a personal watercraft with onboard GPS and echo sounder equipment, in Santa Cruz, California.

USGS ATV is equipped with GPS and collects topographic (elevation) data on Seacliff Beach, Aptos, CA
December 31, 2014

USGS ATV Collecting Topographic Data

Photograph shows a USGS ATV equipped with GPS, ready to collect topographic data on Seacliff Beach in Aptos, California. The pier leads out to the heavily eroded cement ship SS Palo Alto. Various sources reveal that SS Palo Alto was built as an oil tanker by the San Francisco Shipbuilding Company in Oakland, California, and was launched May 29, 1919. She

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location map of Cuyama Valley
December 31, 2014

Cuyama Valley Watershed and Groundwater Basin

Detailed location map of the Cuyama Valley, California watershed and groundwater basin, with the hydrologic model boundary and major rivers.

Mount Shasta, California simplified hazards map showing potential i...
December 31, 2014

Mount Shasta, CA simplified hazards map

Mount Shasta, California simplified hazards map showing potential impact area for ground-based hazards during a volcanic event.

Diagram illustrating how peat loss from reclamation results in land subsidence.
December 31, 2014

Land Subsidence Due to Decomposition of Organic Soils

The dominant cause of land subsidence in the Sacramento-San Joaquin Delta is decomposition of organic carbon in the peat soils. Under natural waterlogged conditions, the soil was anaerobic (oxygen-poor), and organic carbon accumulated faster than it could decompose. Drainage of peat soils for agriculture led to aerobic (oxygen-rich) conditions. Under aerobic conditions,

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USGS scientist inspecting a buckled portion of the Delta-Mendota canal lining
December 31, 2014

Delta-Mendota Canal: Land Subidence Damage

Reduced surface-water availability (associated with droughts) during 1976-77, 1986-92, 2007-09, and 2012-2016 caused groundwater-pumping increases, water-level declines to near or beyond historic lows, and renewed aquifer compaction. The resulting land subsidence has canal buckling and reduced flow capacity of the Delta-Mendota Canal (pictured), the California Aqueduct,

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Lassen Volcanic Center, California simplified hazards map showing p...
December 31, 2014

Lassen Volcanic Center, CA simplified hazards map

Lassen Volcanic Center, California simplified hazards map showing potential impact area for ground-based hazards during a volcanic event.

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USGS
February 20, 2007

Although well aware of the region's earthquake threat, many San Francisco Bay Area residents are perilously uninformed about another dangerous geologic hazard: landslides triggered by heavy rainfall.  The combination of steep slopes, weak rocks, and intense winter rainstorms make the Bay Area uplands an ideal setting for landslides.

USGS
February 1, 2007

Menlo Park, Calif. – The U.S. Geological Survey (USGS) announced today the release of two new publications, both titled, "Protecting Your Family from Earthquakes–The Seven Steps to Earthquake Safety." One is written in Spanish, with an accompanying English translation, and the other is translated into Chinese, Vietnamese, and Korean, also with an accompanying English translation.

USGS
January 30, 2007

Menlo Park, Calif. – Media will be given the opportunity to preview two new earthquake preparedness publications by the U.S. Geological Survey (USGS) prior to wide distribution. The publications are entitled, “Protecting Your Family from Earthquakes–The Seven Steps to Earthquake Safety.”

USGS
January 17, 2007

Earthquake expert Dr Lucy Jones of the U.S. Geological Survey (USGS) will provide the public with her perspective on the next big California earthquake, the lessons learned from Hurricane Katrina, the new Dare to Prepare Campaign and the great risk to the populous Los Angeles basin from a major earthquake on the southern San Andreas Fault.

USGS
January 5, 2007

Major earthquake readiness campaign announced on 150th anniversary of last San Andreas fault earthquake.

USGS
December 11, 2006

New discoveries about Tsunamis, Hurricane Coastal & Barrier Island Destruction, Improved Predictive Modeling for Hazardous Earthquakes and Landslides, Inflating Volcanoes in Hawaii, New Geological Observations of Mars will be featured during 2006 AGU

USGS
October 16, 2006

The U.S. Geological Survey (USGS) and California Geological Survey (CGS) today rolled out three new seismic hazard maps of the Bay Area and announced the online release of important seismic hazard studies resulting from the 1989 Loma Prieta earthquake.

USGS
October 13, 2006

In celebration of Earth Science Week, 1350 students from more than 20 local schools will visit the U.S. Geological Survey (USGS) in Menlo Park on Friday, Oct. 13, from 9:30 a.m. – 2:30 p.m., to meet with scientists for hands-on activities, workshops, and demonstrations.

USGS science for a changing world logo
October 13, 2006

The U.S. Geological Survey (USGS) and California Geological Survey (CGS) will hold a joint media briefing on Monday on important lessons learned from the Loma Prieta earthquake, which occurred October 17, 1989. Three new Seismic Hazard Zone maps will be shown, covering the Menlo Park, Morgan Hill, Palo Alto and Redwood City areas.

USGS
October 13, 2006

The U.S. Geological Survey (USGS) and California Geological Survey (CGS) will hold a joint media briefing on Monday on important lessons learned from the Loma Prieta earthquake, which occurred October 17, 1989. Three new Seismic Hazard Zone maps will be shown, covering the Menlo Park, Morgan Hill, Palo Alto and Redwood City areas. 

USGS science for a changing world logo
September 18, 2006

The U.S. Geological Survey (USGS) released a new report on shoreline change in California, studying more than 450 miles of sandy shoreline. This report is the first to address California´s historic coastal change and coastal land loss or gain for the entire state.

USGS
September 18, 2006

The U.S. Geological Survey (USGS) released a new report on shoreline change in California, studying more than 450 miles of sandy shoreline. This report is the first to address California´s historic coastal change and coastal land loss or gain for the entire state.