No, the Yellowstone supervolcano, the largest caldera in the world (55 by 72 kilometers in size), is not erupting. The alert and danger level of the largest caldera in the world has not changed in any way despite the images that have gone viral on the web that may cause some alarmism.
Yesterday, July 23, 2024, there was a hydrothermal explosion in the “biscuit” basin area, one of the most iconic in the famous American natural park for the presence of thermal water basins and geysers. Hydrothermal explosions are violent events that cause the rapid expulsion of boiling water, steam, mud and fragments of rock that can be thrown into the air up to 2 kilometers high and leave craters of up to two kilometers in diameter. Fortunately, the one that occurred yesterday was a minor explosion.
According to information provided by the USGS, which closely monitors the megavolcano, similar explosions have already occurred several times over the past decades. The most significant occurred in 1989 and 2009. The park is home to the largest known hydrothermal explosion crater on Earth: Mary Bay, on the north side of Yellowstone Lake, is 2.4 kilometers wide and was formed about 13,000 years ago. Large hydrothermal explosions occur on average every 700 years, and at least 25 explosion craters larger than 100 meters have been identified. A rare event, yes, but not that rare.
Luckily, no victims or injuries were reported, but only some damage to the walkway and fences of the trail: however, as the photos published by the national park rangers show, it could have been much worse.