The U.S. Geological Survey (USGS) released its latest earthquake threat assessment this week.
The report now includes 161 volcanoes, eight fewer than it did in 2005. The United States is one of Earth’s most volcanically active countries.
The assessment uses new research to determine which volcanic systems should be added or removed from the list of potentially active volcanoes. It also updates the scoring of active volcanoes to create a “threat ranking.”
The threat assessment puts volcanoes into five threat categories ranging from very low, to high and very high.
The “very low” threat category saw the greatest amount of change, dropping from 32 to 21 active volcanoes. The number of “very high” threats remains the same. 11 of the 18 very-high threat volcanoes are located in Washington, Oregon, or California. Five are near high-population centers in Alaska and two are in Hawai’i.
There are 39 “high” threat volcanoes, including the Yellowstone Caldera, but that group is mostly dominated by Alaskan features.
The high and moderate rated volcanoes could have a substantial effect on national and international aviation, and large eruptions from any of them could cause regional or national-scale disasters.
According to the USGS report, 34 (about 21 percent) of the volcanic systems included in this assessment lie within or partly within land areas managed as national parks or monuments.
The report indicates there are approximately 995 persons living within 30 km of the coordinates given for Yellowstone (not far from Old Faithful geyser). But the public threat to people compounds greatly when you realize 4.25 million visitors toured Yellowstone National Park in 2016.
Similar situations exist for most other national park and national monument volcanoes.