Citizen Scientists: Help CGS Map Landslides

See a landslide? Think C-A landslide, as in

The California Geological Survey (CGS) is asking for the public’s help in pinpointing landslides–which occur in many flavors: rockfalls, rock avalanches, and debris flows–in the state.

February 2019 landslide photo from City of Sausalito, an example photo CGS scientists can use in their map.
February 2019 landslide photo from City of Sausalito.

Landslides are almost a given during the rainy season. That’s especially true in areas that have been impacted by recent wildfires. And if a landslide is fast enough or large enough, it can cause fatalities and hundreds of millions of dollars in damage.

Not every landslide is a disaster. But every landslide interests CGS, which has gone live with a new California “Recent Reported Landslides” interactive map.

screen shot of new CGS recent landslide database showing details submitted to
Screenshot of CGS Recent Landslides database showing details submitted to

Why a new landslide map? A large network of instruments operated by scientific organizations details earthquakes of every size in California, but there is nothing similar for landslides.

The new landslide database relies heavily on input from agencies such as Caltrans, the California Highway Patrol, and – here’s where you come in – crowdsourcing.

How to Contribute a Landslide

If you come across a landslide, first make sure it is safe to stop. Then,

  • Take a few photos of the slide.
    Preferably with something such as a vehicle or tree to provide size perspective.
  • Email the photos to
    Include basic details: the date, the location (a post-mile marker on a highway if no address is available), and a brief description (for example: “debris and mud covered the two-lane road”).
  • Ideal shots include the actual landslide material – rocks, mud, trees, and the like, as well as the source of the slide if observable — rather than a picture taken after the cleanup has occurred.

CGS will follow up quickly on all photo submissions to ensure there are no copyright issues and will verify the occurrence with a team of geologists. Once that happens, the report will go online and scientists will collect additional information for their catalog.

Sending a timely email with your photo(s) to CGS will help in two ways: in the short term, it will increase public awareness and safety. In the long run, it will help scientists develop a more thorough catalog of landslides and piece together why and how often they happen where they do.

“The more data we have, the better we understand the triggers and frequency of landslides and debris flows, which can lead to hazard reduction. Ultimately, that’s the goal.”

CGS Engineering Geologist Paul Burgess

We hope you never see a landslide up close and personal. But if you do, we appreciate your efforts to keep fellow Californians safe and to help our scientists better understand the phenomenon.

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