Yellowstone Records 66 Earthquakes in October, Largest at Magnitude 2.0, as the Caldera Stays at Background Levels
Yellowstone Caldera activity remained at background levels in October, the U.S. Geological Survey's Yellowstone Volcano Observatory said in its monthly update on November 2, keeping the volcano alert level at Normal and the aviation color code at Green for the caldera, which sits mainly in northwestern Wyoming and extends into Montana and Idaho.
The University of Utah Seismograph Stations, which operates the Yellowstone Seismic Network, located 66 earthquakes in the Yellowstone National Park region during October, with no earthquake swarms identified. The largest event was a magnitude 2.0 micro earthquake on October 4 at 5:32 p.m. MDT, about 15 miles south of West Thumb in Yellowstone National Park.
Continuous GPS data showed little net deformation of the caldera or the north caldera rim over the past several months, with subtle variations probably caused by seasonal changes, especially in groundwater conditions.
Hydrothermal features were busier. Giant Geyser in the Upper Geyser Basin, the second tallest geyser in the park, erupted three times in October, on October 5, 13 and 22. Echinus Geyser in Norris Geyser Basin erupted on October 26, and the small hot pool that formed after the June 13 hydrothermal explosion in Biscuit Basin had at least two small eruptions. Steamboat Geyser in Norris, by contrast, was characterized by minor eruptions and has had only one major eruption so far in 2026.
The observatory, whose scientist-in-charge is Michael Poland, is a partnership of the USGS, Yellowstone National Park, the University of Utah, the University of Wyoming, Montana State University and other agencies, and provides long-term monitoring of volcanic and earthquake activity in the Yellowstone region. (Source: U.S. Geological Survey)
Source: U.S. Geological Survey
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Photo: 图：黄石国家公园的 Giant 间歇泉正在喷发。Wikimedia Commons 图片（CC BY-SA 2.0，John Manard）。 / Photo: Giant Geyser erupting in Yellowstone National Park. Image via Wikimedia Commons (CC BY-SA 2.0, John Manard).
