​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​CGS News and Announcements

​Announcements are sorted by publish date, in ​de​​​scending order; i.e. newest at the top, oldest at the bottom.​​​​

collapse Year : 2018 ‎(6)

Earthquake Hazards Search just got easier​ ​

California Geological Survey unveils web application to help public locate Earthquake Hazard Zones

Posted: 3/21/2018 10:00 AM

​​​​​​​​​The California Earthquake Hazards Zone Application is an online map that allows anyone with a computer, tablet or smartphone to conveniently check whether a property is in an earthquake hazard zone. With this tool, you can type in an address or use the location capability of your computer or mobile device to determine whether a pro​perty lies within any of CGS’s mapped earthquake hazard zones. It will also tell you if CGS has not yet evaluated the hazards in that area.

Follow this link to explore the California Earthquake Hazards Zone Application​​

​​​Anniversary of the 1933 Long Beach Earthquake​

Posted: 3/10/2018 8:00 AM

​​​​On March 10, 1933, a large earthquake tore thru the city of Long Beach, California. Extensi​ve damage to schools prompted the California State Legislature to pass the Field Act just one​ month after the earthquake. The Field Act authorizes the Divisio​n of the State Architect (DSA) to review and approve all public school plans and specifications and to furnish general supervision of the construction work. The California Geological Survey assists the DSA by reviewing geologic hazards affecting schools subject to the Field Act.​

Follow this link to learn more about the 1933 Long Beach Earthquake and the Field Act​​

​​​Speci​al Report 240 - Update of Mineral Land Classification: Portland Cement Concrete-Grade Aggregate in the Western San Diego County Production-Consumption Region of California​

Posted: 2/16/2018 8:00 AM

​​​​​California's Surface Mining and Reclamation Act of 1975 (SMARA) requires the State Geologist to classify land into Mineral Resource Zones (MRZs), based on the known or inferred mineral resource potential of that land. The primary goal of mineral land classification is to help ensure, through appropriate local lead agency policies and procedures, that mineral resources will be available when needed and do not become inaccessible because of inadequate information during the land-use decision‑making process.​

This report is the third in a series of regional mineral land classification reports for portland cement concrete (PCC)-grade aggregate for the Western San Diego County Production-Consumption Region (P-C Region).  It updates the mineral land classification of the region, reevaluates the region's PCC-grade aggregate resources, and includes an updated 50‑year projection of construction aggregate demand for the P-C Region through the year 2065.

Download the full release statement​

Links to the Report and Maps

Download Special Report 240 (SR 240) - 2017 Update of Mineral Land Classification: Portland Cement Concrete-Grade Aggregate in the Western San Diego County Production-Consumption Region, California

Download Plate 1 - Updated (2017) Mineral Land Classification Map for Western San Diego County

Download Plate 2A - Updated (2017) Aggregate Resource Sector Map for Western San Diego County​ - Northern Part

Download Plate 2B - Updated (2107) Aggregate Resource Sector Map for Western San Diego County​​​ - Southern Part

​​2018 Tsunami Preparedness Week​ is coming!

Posted: 1/19/2018 8:00 AM

​​​​​​March 26-30, 2018 is Tsunami Preparedness Week. Information for emergency managers, educators, and the public is available on CGS's Tsunami Preparedness page.

Follow this link to learn more about Tsunami Preparedness

​Major Revision t​o California Guide for Assessing Fault Rupture Hazards​​​​

Posted: 1/11/2018 8:00 AM

​​​​​​​​​​​​​​​​​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.​

Download 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 (2018)

​Several New and Revised Official Alquist-Priolo​ Earth​q​uake Fault Zone maps and Seismic Hazard Zone maps​​

Posted: 1/11/2018 8:00 AM

​​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.​​​

Follow this link to download the maps, reports and GIS data

collapse Year : 2017 ‎(7)

​​SMIP17 Seminar on​ Utilization of Strong Motion Data​​

Posted: 10/19/2017 8:00 AM

​​​​​​​​​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.​​​​

Follow this link to learn more about SMIP seminars

​​Pr​eliminar​y Geolo​gic Map of the Cedarville 30’ × 60’ Quadrangle, Modoc County, California​

Posted: 10/9/2017 8:00 AM

​​​​​​​​​​​​The Pr​eliminar​y 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 Ced​arville 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.​​

Download Pr​eliminar​y Geologic Map of the Cedarville 30’ × 60’ Quadrangle, Modoc County, California

Download companion pamphlet containing explanatory text, tables and figures

Geologic Map of t​he Independence Lake and Hobart Mills 7.5’ Quadrangles, Sierra and Nevada Counties, California

Posted: 10/9/2017 8:00 AM

​​​​​​​​​​​​​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.​​

Follow this link to order the map​ or other CGS Publications

California ranks six​th among the states in ​Non-Fuel Mineral Production in 2015

Posted: 7/28/2017 8:00 AM

​​​​​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.​​​

Download 2015 California Non-Fuel Minerals report

W​eb Services f​or Alquist-Pr​iolo Earthquake Fault and Seismic Hazard Mapping Zones

Posted: 7/27/2017 8:00 AM

​​​​The California Geological Survey (CGS) is pleased to announce the release of earthquake regulatory zone maps as a web services product that can be incorporated into geographic information systems (GIS). Access to these maps via the internet provides an alternative to downloading individual 7.5-minute quadrangle maps and an automated way to maintain the most up-to-date versions on individual systems. 

The web-based earthquake hazard zone maps include:

  • Alquist-Priolo Earthquake Fault Zones
  • Alquist-Priolo Earthquake Fault Zone Fault Traces
  • Seismic Hazard Zones for Earthquake-triggered Landslides
  • Seismic Hazard Zones for Liquefaction
  • Seismic Hazard Zones for Overlapping Areas of Landslide and Liquefaction
  • Areas not evaluated for Landslide and Liquefaction Hazards.

Click here to access the earthquake hazard zone map data

Attributes included with ​these data provide links to reports on how the maps were prepared and to the PDF cartographic versions. Metadata pages are available at:

Access to the 7.5-minute quadrangle tile data is still available through the CGS Information Warehouse (http://maps.conservation.ca.gov/cgs/informationwarehouse​). These data include GIS Shapefiles and metadata, GeoPDF cartographic maps, as well as associated reports.

​Geological Gems of the California State Parks interactive web map

Posted: 4/19/2017 8:00 AM

​​​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.​

Follow this link to explore the GeoGems interactive map​

​​Updated Map Products for Alquist-Priolo Fault and Seismic Hazards Mapping Zones

Posted: 4/13/2017 8:00 AM

​​The CGS Seismic Hazards Program is pleased to announce a complete revamping of all regulatory earthquake hazard zone GIS files available through the CGS Information Warehouse. A significant upgrade also has been made to PDF versions of zone maps – Alquist-Priolo fault rupture hazard zones have been combined with liquefaction and earthquake-triggered landslide zones in 7.5-minute quadrangles where multiple zone types exist.

The CGS Seismic Hazards Program has significantly updated two versions of its regulatory hazard zone map products. First, all GIS data files (in ESRI Shapefile format) for fault rupture, liquefaction and earthquake-induced landslide zones have been re-projected to California (Teale) Albers, in meters, with a North American Datum 1983. In addition, all GIS zone polygons now include attributes that provide the name of the 7.5-minute quadrangle, map release date(s), and links to zone reports and PDF maps. Active fault traces within earthquake fault zones have attributes for fault name and fault type.

A second significant upgrade has been made to PDF versions of zone maps in counties where there are overlapping fault rupture, liquefaction and earthquake-induced landslide zones, and where official zone maps have been prepared since 2012. These PDF maps allow users to turn layers on and off to create custom displays. The updated map products can be viewed and downloaded from the CGS Information Warehouse.

Follow this link to explore the CGS Information Warehouse

NOTE: By adding the free TerraGo Toolbar to Acrobat Reader, users can read zone map attributes and other geographic information. Features of the TerraGo Toolbar include:

  • Toggle layers on/off
  • View coordinate displays for over 300 coordinate systems regardless of underlying coordinate system for the GeoPDF
  • Identify and search for attributes within layers
  • Coordinate searches
  • Length and area measurements
  • Drawing and Markups on the map which can be saved as shapefiles and other vector formats to later be imported into ArcGIS​

Click here to learn how to obtain, install and use the free TerraGo Toolbar

collapse Year : 2016 ‎(6)

​​In Memory of Jeffery Owen ​Tambert, 1942-2016

Posted: 8/30/2016 8:00 AM

​​​​​​​​​​We remember our friend and colleague Jeffery Owen Tambert ​who passed away on July 16, 2016.​​ 


​In Memory of Dr. M. Lee Allison, 1948-2016

Posted: 8/25/2016 8:00 AM

​​​​​​CGS sadly recognizes the passing of Dr. M. Lee Allison, State Geologist and Director of the Arizona Geological Survey. 

Download the Arizona Geological Society's tribute to Dr. Allison​

​CGS Publications Discontinues​ Walk-In Sales at Field Offices

Posted: 8/15/2016 8:00 AM

​​​​​Effective September 6, 2016, walk-in sales services at the ​CGS field offices will be discontinued. 

Please visit our ​Publica​tions page​ for information about ordering CGS Publications.​​​​​

​In Memory of Tom Montgomery ​Wootton, 1921-2016

Posted: 6/2/2016 8:00 AM

​​​​​​​​​We remember our friend and colleague Tom Montgomery Wootton who passed away on May 31, 2016.​​​ 


​In Memory of Earl William Hart, ​1927-2016

Posted: 1/26/2016 8:00 AM

​​​​​​​We remember our friend and colleague Earl William Hart who passed away in early January.​​​ 


​California Land​slide Inventory Update

Posted: 1/21/2016 8:00 AM

​​​​​The California Landslide Inventory has been updated to include new geographic areas, and many smaller landslides.​​

Follow this link to explore the California Landslide Inventory

collapse Year : 2015 ‎(4)

​​Index to California Mines ​in the Mining and Scientific Press​

Posted: 12/18/2015 8:00 AM

​​​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.​

Click here to explore the M&SP index

​Web Map: Wildfire Perimeters and Deep Landslide Susceptibility​

Posted: 11/10/2015 8:00 AM

​​​​​CGS released a web map in collaboration with CalFire showing recent wildfire perimeters and deep landslide susceptibility.​​

Follow this link to explore the Wildfire Perimeters and Deep Landslide Susceptibility web map

​Interactive web maps fo​r the 2010 Fault Activity Map and 2010 Geo​logic Map of California​​

Posted: 7/28/2015 8:00 AM

​​​​​​CGS released updated interactive web maps for the 2010 Fault Activity Map and 2010 Geo​logic Map of California. The map services used in both maps are publicly available through ArcGIS Online.​

Click here to explore the 2010 Fault Activity Map of California

Click here to explore the 2010 Geologic Map of California

​2015 Update to the Long-term Earthquake Forecast for California

Posted: 3/10/2015 8:00 AM

​​​​​​​​​USGS, CGS, and SCEC have updated the Third California Earthquake Rupture Forecast (UCERF3)​. 


collapse Year : 2014 ‎(7)

​Publication Release: ​M​ap Sheet 62-Geology of Ring Mountain and Tiburon Peninsula

Posted: 12/30/2014 8:00 AM

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 ser​pentinized 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 M​ountain 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).

Click here to order Map Sheet 62-Geology of Ring Mountain and Tiburon Peninsula

​Publication Release: Map S​heet 61-Geologic Map of Part of Eastern Placer County, Northern Sierra Nevada

Posted: 11/7/2014 8:00 AM

​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.

Click here to order Map Sheet 61-Geologic Map of Part of Eastern Placer County, Northern Sierra Nevada

​South Napa​ Earthquake

Posted: 8/24/2014 8:00 AM

​​​​​South Napa Earthquake, magnitude 6.0, 3:20 a.m.

Click here for more information, photos, and CGS field response

​In Memory of Rodger ​Chapman, 1925-2014

Posted: 8/18/2014 8:00 AM

​​​​​​​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.


​Earthquake Sc​enarios for the Long Valley Caldera-Mono Lake area

Posted: 6/30/2014 8:00 AM

​​​​​​​​​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.​​

Download Earthquake Scenarios for the Long Valley Caldera-Mono Lake area​

​CGS Schoo​l Project Reviews

Posted: 2/25/2014 8:00 AM

​​​​​​​​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.​


​Northridge Earthquake ​20th Anniversary

Posted: 1/17/2014 8:00 AM
collapse Year : 2013 ‎(4)

Tsunami Scenario: Magnitude 9 Alaska Earthquake

Posted: 9/4/2013 8:00 AM

​​​​​​​​​​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. 


​Find CGS Maps and Reports at the Inf​ormation Warehouse​​​​​

Posted: 7/5/2013 8:00 AM

​​​​​CGS has developed a tool that allows you to search ALL of their Regulatory, Landslide, Tsunami and SMARA (mineral classification) maps using one ​interface.​​

Follow this link to explore the CGS Information Warehouse​

​​In Memory of ​Wesley G. Bruer, 1926-2013​​​​

Posted: 1/9/2013 8:00 AM

​​​​​​​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. 


Posted: 1/1/2013 8:00 AM