Oct. 25 (UPI) -- The United States has 18 volcanoes listed as a "very high threat" to their surrounding communities, according to recent list compiled by the United States Geological Survey.
Those volcanoes sit in five states, with Hawaii's Kilauea at the top of the list.
Kilauea last erupted in May 2018 for several hours following a magnitude-5.0 earthquake on Hawaii. The eruption filled nearby neighborhoods with dangerous gas and lava, forcing more than 10,000 residents to evacuate.
The other states with volcanoes at very high threat levels are Alaska, California, Oregon and Washington.
The U.S. has 161 active volcanoes, and has experienced 120 eruptions and 52 incidents of volcanic unrest since 1980.
The U.S. Geological Survey uses 24 hazard and exposure factors to assess and publish volcanic threat based on factors that include: field and laboratory research that includes or takes off volcanoes from the list of possibly active volcanoes, and updates the risk factors used to compile the volcano threat ranking.
The threat ranking doesn't predict when volcanoes will erupt.
The USGS has added and raised the threat level assessment for 12 volcanoes, and lowered or removed 20 volcanoes from the list. The agency uses the list to help federal, state and local government officials, along with the National Volcano Early Warning System, to prepare risk mitigation efforts.