The Long Valley Caldera, a volcano in Mono County, California, has been a subject of concern due to geological changes and increased seismic activity. While it’s classified as a “very high threat” volcano by the U.S. Geological Survey, experts say there’s no immediate risk of a supervolcanic eruption.
The caldera, formed over 760,000 years ago by a super-eruption, has been showing signs of activity, including earthquakes and ground fluctuations, over the past four decades. But these signs don’t necessarily indicate an imminent eruption.
Caltech researchers, who recently published their findings in the journal Science Advances, used high-resolution underground images and seismic data to assess the situation. They concluded that the increased seismic activity and ground movement are likely caused by the cooling and crystallization of magma underground, releasing gas and liquid that trigger earthquakes and small eruptions. This process, while active, does not suggest a supervolcanic event.
The Long Valley Caldera, situated about 40 miles east of Yosemite Valley, is being closely monitored. The magma underneath the area is cooling and contracting, indicating a lower risk of a major eruption. Experts point out that there are other pockets of magma in the region, and earthquake swarms remain a concern.
Northern California’s other volcanoes – Mt. Shasta and Lassen Peak – also pose risks. Volcanic ash from eruptions could disrupt electricity supply, transportation, and water sources, affecting a wide area.
Both Shasta and Lassen are active, with Shasta being designated a “very high threat” from the U.S. Geologic Survey. Lassen Peak remains the most visibly active volcano, with destinations like Sulphur Works and Bumpass Hell showing the underground volcanic activity for anyone who visits. But due to its recent eruption in 1915, a large eruption is not likely anytime soon.
While the chances of a supervolcanic eruption in California are low, monitoring and research continue to ensure preparedness for any volcanic activity in the region.