Landslide Risk Evident in Newly Released Map

Landslides cause an estimated 25 to 50 deaths and over $2 billion damage per year in the United States.

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    NEWSLETTERS

    TK
    For these homeowners in Southern California, the landslide risk is obvious.

    The California Geological Survey released new maps Thursday that are supposed to show what areas are most at risk of landslides.

    The difference between this map and other maps released by the agency that watches the potential for ground slippage is that it shows the relative likelihood of deep landsliding based on regional estimates of rock strength and steepness of slopes without taking into account mother nature.

    For instance, it does not factor in heavy rain or earthquakes. It also only looks at the risk in a general area and not a specific location.

    The people who put the map together said that is their next step.

    "The next things we want to look at are the triggers. What are the rain storms that could trigger these landslides and the earthquakes that could trigger these landslides. So we will be moving forward with this map and creating hazard potential maps after this," Timothy McCrink said.

    When you look at Bay Area portion of the map, you notice the most red, or danger, areas in the county of Marin and the least red areas in San Mateo County.

    See the map at this link.

    The map ranks areas on a scale of 0 to 10 combining factors of rock strength and degree of slope.  The greater the slope and the weaker rock equals the highest susceptibility.

    The areas that have the greatest risk of landslides are the coastal mountains between San Francisco and L.A, as well as the coastal range north of the Bay Area up to the Oregon border.