Unified Interior Regions


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.

States L2 Landing Page Tabs

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Poster with illustrations of the underwater part of a bay, with text about the work done in the area.
December 31, 1998

Mapping Shipping Hazards in San Francisco Bay, 1997-1998

Large-scale poster describing USGS work.

The USGS mapped western San Francisco Bay using sonar, in cooperation with the National Oceanic and Atmospheric Administration (NOAA) and C&C Technologies. Some parts of the Bay floor are so shallow that a large tanker or container ship could run aground at low tide and create a massive oil spill.

The maps show how

View of the Mono Lake-Long Valley volcanic region
December 31, 1997

View of the Mono Lake-Long Valley volcanic region

An aerial view looking south of the Long Valley volcanic region in the area of Mono Lake, showing a line of rhyolite lava domes and explosion craters. An inset map shows the locations of silcic magmatic centers in the Long Valley area.

Image: Coso Volcanic Field Tumulus
October 1, 1997

Coso Volcanic Field Tumulus

A tumulus in the Coso Volcanic Field, California. This lava was probably more viscous than the lava found in the Hawaii tumuli.

Tumuli are structures usually associated with slow-moving flows. When the top of the flow crusts over, the lava beneath can well upward and create an elliptical, domed structure. Oftentimes, the pressure creates an axial fracture along the

Image: Rubens coil in the Rock Magnetics Laboratory in Menlo Park, California
December 1, 1995

Rubens coil in the Rock Magnetics Laboratory in Menlo Park, California

Rubens coil inside the Rock Magnetics Laboratory on the USGS Menlo Park campus. The function of the Rubens coil is to cancel the earth's magnetic field for thermal demagnetization of core samples. It is constructed of nonmagnetic materials and the control unit is place far enough away from the instrument to avoid interference from its metal components.

During the

Image: Northridge, CA Earthquake Damage
January 1, 1994

Northridge, CA Earthquake Damage

Collection of USGS still images taken after the January 17, 1994 Northridge earthquake highlighting the damage to buildings and infrastructure.

Attribution: Natural Hazards
Photo shows the major collapse of a building following an earthquake, the building has fallen onto and crushed a car completely.
December 31, 1989

Loma Prieta earthquake, Marina District

An automobile lies crushed under the third story of this apartment building in the Marina District. The ground levels are no longer visible because of structural failure and sinking due to liquefaction.

Mount Konocti on the western shore of Clear Lake, California
December 31, 1975

Mount Konocti on the western shore of Clear Lake, California

Mount Konocti, a mostly dacitic composite cone, on the western shore of Clear Lake, California. Thurston Lake is in the foreground.

December 31, 1969

Tremolite Asbestos

Tremolite asbestos, Death Valley, California.

Three men stand in front of a single-engine airplane in an open field.
December 31, 1965

Three geologists and a plane

Three pioneers of USGS geological studies, in 1965, from left to right: Parke D. Snavely, Jr., Robert E. Wallace, and Thomas W. Dibblee, in front of a 1964 Cessna 182G Skylane.

Photo of a low, one-story building with windows and a big front entrance reading Wm. Wrigley Jr. Co.
December 31, 1955

Front of the William Wrigley, Jr. Company building in west Santa Cruz

Front of the Wm. Wrigley Jr. Co. building in 1955, now home to the USGS Pacific Coastal and Marine Science Center.

A building after an earthquake has crumbled the roof and brick walls, the interior is now visible.
March 26, 1933

Long Beach Earthquake Damage

View of John Muir School on Pacific Avenue in Long Beach, California, showing damage from the March 10, 1933 Long Beach earthquake. Photo taken 8 days after the earthquake, on March 18, 1933. Photo by W.L. Huber, USGS.

Coso hot springs, black and white image
February 4, 1920

Coso Hot Springs located at Coso Volcanic Field, CA

Coso Hot Springs in Coso volanic fields, Feb 4, 1920.

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December 3, 1997

Free public lecture: U.S. Geological Survey Geologist Henry Moore presents the latest "dirt" on Mars; viewing Mars from Sojourner at 7 P.M. in the City Council Chambers, 701 Laurel Street, Menlo Park, Calif.

November 25, 1997

All offices of the U.S. Geological Survey will be closed Thursday, of course, to observe the Thanksgiving holiday, but will be open as usual on Friday, November 28.

October 29, 1997

The U.S. Geological Survey (USGS) today joined forces with other federal and state agencies to announce specific efforts to implement recommendations of this summer’s Lake Tahoe Presidential Forum, including creation of an Internet-based clearinghouse of scientific information for the Lake Tahoe area.

October 21, 1997

The presence of 125,000-year-old microfossils in the muds of San Francisco Bay may help engineers decide where and how to rebuild the San Francisco-Oakland Bay Bridge, according to a U.S. Geological Survey(USGS)scientist in Menlo Park, Calif.

September 2, 1997

The effects of ground-water development on ground-water levels and ground-water quality in the town of Atherton, Calif., is the focus of a report released by the U.S. Geological Survey , Department of the Interior.

August 8, 1997

More than 200 exhibits dealing with topics from ocean floor photography to the geology of Mars will be highlighted at the U.S. Geological Survey’s open house at its Western Region Center in Menlo Park, Calif., September 13 and 14. 

August 8, 1997

The U.S. Geological Survey needs help to prepare for and assist at its big open house, September 12, 13 and 14, at the USGS Western Region Center in Menlo Park.

July 16, 1997

Experience over the last several years with the current system for describing the level of geologic unrest, such as earthquake swarms, ground deformation and gas emissions in the Long Valley caldera of eastern California, has shown it to be awkward and susceptible to misinterpretation by both the news media and the public.

July 8, 1997

A team of Bay Area earthquake scientists will be looking for more than old golf balls when they open an exploratory trench on the second fairway of the Mira Vista golf course in El Cerrito, this week. Golf course officials have rerouted the sedonc hole in order to give the geologists a 10-day window for the study.

May 29, 1997

Selected, local editions of U.S. Geological Survey topographic maps will be available for purchase at the USGS exhibit that will be part of the San Francisco Bay Trail Project’s National Trails Day Festival, Saturday, June 7, at Robert Crown Memorial State Beach and Crab Cove Visitor’s Center in Alameda.

April 15, 1997

Peat soils in the Sacramento-San Joaquin Delta and their relationship to water quality; the history and consequences of long-term groundwater use in the Mojave Desert; the hydrology, biology and geology of San Francisco Bay; 

April 15, 1997

Dr. Gordon Eaton, the national director of the U.S. Geological Survey in Reston, Va., will be one of the speakers at the Friday, April 18, 1997 dedication of Placer Hall on the California State University at Sacramento campus.