| Year : 2018 (2)
CGS released two new and two revised Official Alquist-Priolo Earthquake Fault Zone maps, and eight new and two revised Official Seismic Hazard Zone maps.
Areas covered by new and revised AP Earthquake Fault Zone maps are within Los Angeles and Napa counties, and affect the cities of Beverly Hills, Culver City, Los Angeles, Napa, Santa Monica, Vallejo, and West Hollywood.
Areas covered by new and revised Seismic Hazard Zone maps are within Contra Costa, Riverside and San Mateo counties, and affect the cities of Antioch, Belmont, Brentwood, Burlingame, Foster City, Hillsborough, Menlo Park, Murrieta, Oakley, Redwood City, San Carlos, San Mateo, and Temecula.
CGS released a major revision to its Special Publication 42 (SP 42): Earthquake Fault Zones - A Guide for Government Agencies, Property Owners / Developers, and Geoscience Practitioners for Assessing Fault Rupture Hazards in California. SP 42 has been the primary guidance document since 1975 for providing background regarding the Alquist-Priolo Earthquake Fault Zoning Act (AP Act) and the assessment of surface fault rupture hazard. The 2018 edition is the latest update to this document, with a focus on providing more detailed guidance to government agencies, property owners, and geoscientists who are affected by the AP Act. This edition is freely available on the CGS website as a pdf download.
| Year : 2017 (6)
CSMIP (California Strong Motion Instrumentation Program) holds annual seminars to transfer recent research findings on strong-motion data to practicing seismic design professionals, earth scientists and earthquake response personnel as part of its Data Interpretation Project. This seminar was held on October 19th at UC Berkeley. The seminar’s program included an invited presentation on the recent damaging Mexico earthquake.
The Preliminary Geologic Map of the Cedarville 30’ × 60’ Quadrangle, Modoc County, California, by Thomas L.T. Grose, Anne E. Egger, and Matt D. O’Neal, is available as a downloadable PDF file with a companion pamphlet.
The Cedarville Quadrangle is the fourth and final map in a series of adjacent geologic maps, including (from south to north): Susanville, Eagle Lake, Alturas, and Cedarville. The Cedarville Quadrangle spans portions of the Basin and Range and Modoc Plateau geomorphic provinces, and is largely underlain by Tertiary age volcanic rocks and associated volcaniclastic sedimentary rocks. Major geologic features of the area include the Devils Garden Plateau, a region of horizontal strata with little structural relief, the Goose Lake Valley graben, the north-south – trending horst of the Warner Range and the Surprise Valley half graben. The Surprise Valley fault between the Warner Range and Surprise Valley is characterized by fresh scarps in modern alluvium associated with Holocene activity.
CGS is pleased to announce the release of a new geologic map, Geology of the Independence Lake and Hobart Mills 7.5’ Quadrangles, Sierra and Nevada Counties, California (Map Sheet 63), by Arthur Gibbs Sylvester and Gary L. Raines. The map is available only as a printed product from CGS Publications. Price is just $30 each.
This new map covers a portion of the northern Sierra Nevada, just north of Donner Lake and the town of Truckee. The map represents the work of the authors with contributions from 32 students and graduate teaching assistants. Cretaceous hornblende-biotite granodiorite, Miocene and Pliocene andesitic lava flows and volcaniclastic deposits are the principal rock types in the map region. Large areas are covered with Pleistocene glacial drift related to at least three stages of glaciation. Two major fault zones strike northwestward through the region. The faults represent the westward incursion of Basin and Range faulting into this part of the northeastern Sierra Nevada.
In 2015, California non-fuel mineral production accounted for approximately 4.2 % of the United States total. There were 717 active mines in the state and the total market value of production was $3.6 billion.
The CGS Seismic Hazards Program is pleased to announce it has released all of its regulatory hazard zone data as web-based services.
California is a veritable treasure chest of nationally acclaimed natural landmarks and much adored scenery. This geologic legacy on display in the landscape can be observed throughout California's State Park system. The mission of California State Parks is "to provide for the health, inspiration and education of the people of California by helping to preserve the state's extraordinary biological diversity, protecting its most valued natural and cultural resources, and creating opportunities for high-quality outdoor recreation."
We selected exemplary units of the State Park system to highlight California's geologic legacy. The selected parks are dubbed "GeoGems." CGS Special Report 230 is a collection of more than fifty short articles explaining the geologic features of the "GeoGems" for the public.
| Year : 2016 (6)
We remember our friend and colleague Jeffery Owen Tambert who passed away on July 16, 2016.
CGS sadly recognizes the passing of Dr. M. Lee Allison, State Geologist and Director of the Arizona Geological Survey. Click the article title to view the Arizona Geological Society tribute to Dr. Allison.
Effective September 6, 2016, walk-in sales services at the CGS field offices will be discontinued. Please visit our Publications page for information about ordering CGS Publications.
We remember our friend and colleague Tom Montgomery Wootton who passed away on May 31, 2016.
We remember our friend and colleague Earl William Hart who passed away in early January.
The California Landslide Inventory has been updated to include new geographic areas, and many smaller landslides.
| Year : 2015 (4)
The Index to California Mines in the Mining and Scientific Press is now available online. This index provides access to records of historic mine activity (1860-1922) in California.
CGS Released a new web map in collaboration with CalFire showing recent wildfire perimeters and deep landslide susceptibility.
CGS released updated interactive web maps for the 2010 Fault Activity Map and 2010 Geologic Map of California. The map services used in both maps are publicly available through ArcGIS Online.
USGS, CGS, and SCEC announce new long-term earthquake forecast for California.
| Year : 2014 (7)
Highly detailed geologic maps by David Bero of Sonoma State University cover the classic locality of Ring Mountain as well as the Tiburon Peninsula, located in southern Marin County, California. This area is well known for the number and variety of high-grade metamorphic blocks within the Franciscan Complex. The variety of temperature and pressure conditions recorded by the metamorphic blocks at Ring Mountain have made this area a key laboratory for the understanding of the subduction process represented by the surrounding Franciscan Complex. Detailed geologic mapping and petrographic analyses reveal that Ring Mountain and the Tiburon Peninsula are underlain by four distinct structural units separated by low-angle faults. The structurally highest unit consists of partially serpentinized peridotite (harzburgite), a possible remnant of the Coast Range Ophiolite. The underlying unit is the structurally thin Ring Mountain serpentinite-matrix mélange. Entrained within, and commonly eroded from, the mélange matrix are exotic blocks of variable size, shape, and metamorphic grade. The Ring Mountain serpentinite-matrix mélange is underlain by the Tiburon Ridge Terrane, consisting of blueschist facies, schistose metagraywacke and related lithologies. The structurally lowest unit within the area, referred to as the Metalitharenite of Reed Station, is dominated by prehnite-pumpellyite facies metalitharenite. These maps, focused on the geology and structure of Ring Mountain and the adjoining Tiburon Peninsula, provide background and context for numerous detailed studies.
This report is available as printed maps at 1:6,000 and 1:12,000 scales with an accompanying 34 page pamphlet. A limited number of rolled maps are available on request (please specify when ordering; additional shipping and handling costs apply).
This geologic map shows the distribution of major rock types that make up the Sierra Nevada
in part of eastern Placer County, west of Lake Tahoe and south of Interstate 80. Topographically,
the western slope of the Sierra Nevada is relatively gentle, while the eastern slope is steep and
broken by late Cenozoic faults along which the range is being uplifted and tilted westward. Part of
the eastern range-front fault system crosses the map area between Donner Pass and Lake Tahoe
and separates large tracts of Paleozoic and Mesozoic metamorphic and plutonic rocks exposed in
the west from Tertiary and Quaternary volcanic rocks in the Truckee and Tahoe basins to the east.
Metamorphosed Paleozoic and Mesozoic oceanic and volcanic-arc rocks are exposed over much of
the map area. These include parts of the Shoo Fly Complex, an accretionary prism of oceanic rocks
and trench-fill deposits, overlying volcanic arc rocks of the
Taylorsville sequence and later Permian and Mesozoic rocks.
Intruding the metamorphic rocks are plutonic rocks of the Sierra
Nevada batholith, which range in age from Middle Jurassic to Early
Cretaceous. Tertiary volcanic rocks unconformably overlie the
metamorphic and plutonic rocks in large parts of the mapped area.
Evidence for four periods of Pleistocene glaciation is recognized in
extensive moraine, till, and outwash deposits along the upper
Truckee River and its tributaries.
This publication is available as a printed map at 1:48,000 scale
with an accompanying 37 page pamphlet.
South Napa Earthquake, magnitude 6.0, 3:20 a.m. Click the article title for more information, photos, and CGS field response.
In memory of Rodger Chapman (1925-2014). Rodger established and supervised the CGS Geophysics Program, which contributed greatly to our understanding of the subsurface geology of California.
As part of the USGS multi-hazards project in the Long Valley Caldera-Mono Lake area, CGS developed several earthquake scenarios and evaluated ground shaking, surface fault rupture, liquefaction, and landslide hazards associated with these earthquake scenarios.
CGS can now accept electronic submittal of school projects. In addition, the 2013 CBC requires a “Site Data Report” be submitted. Click the article title to see more information about submitting school projects for CGS review.
| Year : 2013 (4)
CGS has partnered with the USGS and the Southern California Earthquake Center in the Working Group for California Earthquake Probabilities to produce the Uniform California Earthquake Rupture Forecast version 3, a new evaluation of the seismic shaking potential in California.
CGS has partnered with the USGS Science Application for Risk Reduction (SAFRR) project to evaluate the effects of a statewide tsunami scenario generated by a magnitude 9 earthquake off Alaska.
CGS has developed a tool that allows you to search ALL of their Regulatory, Landslide, Tsunami and SMARA (mineral classification) maps using one interface.
Wesley G. Bruer, California State Geologist and Chief of the California Division of Mines and Geology (California Geological Survey) from 1969 to 1973, passed away on January 4, 2013.