The U.S. Geological Survey is updating its volcano threat assessments for the first time in 13 years.
Four volcanoes in California are now considered to be a very high threat.
Those include Mount Shasta in Northern California, which ranks as number five on a list of the 18 U.S. volcanoes.
Mount Shasta is of particular concern because more than 100,000 people live or work in this hazard zone.
An estimated 37-million cars also pass by on Interstate-5 each year.
There are two more in California Lassen Volcanic Center, also in Northern California, which stands at number 11.
Long Valley Caldera near Mammoth Mountain at number 18.
Hawaii's Kilauea Volcano, which has been erupting this year, tops the danger list.
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