​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​Welcome to the California Geological Survey

​​​​​​​​​​​​THE CALIFORNIA GEOLOGICAL SURVEY is one of the oldest geological surveys in the United States, having been established in 1860. We map and analyze data on the state's diverse geologic environment, earthquakes, and other geologic hazards and mineral resources to provide critical information to protect life, property, commerce, and the environment from natural hazards. The California Geological Survey is regarded as the primary source of geologic information used for decision-making by California's government agencies, its businesses, and the public.

–“A​LTIORA PETIMUS”​ ​(We Reach Higher​​)

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CGS​ ​​​News​

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​​

​​​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

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.

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