A man visiting Yellowstone National Park captured the moment a chunk of rock broke away from the side of El Capitan, triggering a huge cascade of debris that left trails unusable. The video, which you can watch below, was recorded by Alex J Wood, who shared it on Twitter earlier this week.
Following the rockslide, the National Park Service (NPS) has advised visitors to consider their hiking plans carefully and not stray into the surrounding backcountry.
"The area from approximately El Capitan picnic area to El Capitan Crossover, on the north side of the Merced River, is closed due to a rockfall," it said. "The Lower Yosemite Fall loop trail is open, however off-trail areas remain closed. Please remain on the trail."
Avalanche! Crazy seeing giant piece of El Capitan fall at @YosemiteNPS @NBCNews @CNN @ABC #yosemite #yosemitenationalpark #rock #Avalanche @BBCWorld #elcapitan pic.twitter.com/9fVgQmDXvSFebruary 21, 2023
According to the Colorado Geological Survey, if just one or two rocks come loose (which happens all the time) then it's a rockfall, but if a large mass of rock, soil and other material falls then it's a rockslide. They can be triggered by various factors, including seismic activity, erosion (subterranean or above ground), mining, and glacial recession.
Rockslides are considered a serious geologic hazard, and claim 20-50 lives each year in the US. Most deaths caused by rockslides happen on roads rather than hiking trails, but a hiker was tragically killed in 2017 by a chunk of rock that fell from El Capitan onto a trail below, and in 2013 a family was killed by a rockslide on a popular hiking trail in Colorado.
To stay safe, hikers are advised to avoid walking on steep, rocky terrain during the spring thaw, or following heavy rains. You should also avoid areas where there is evidence of recent rockfalls, and try not to walk directly below steep terrain where others are hiking directly above you. For more advice, see our guide what are rockslides and are they a threat to hikers.
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Cat is the editor of Advnture, She’s been a journalist for 15 years, and was fitness and wellbeing editor on TechRadar before joining the Advnture team in 2022. She’s a UK Athletics qualified run leader, and in her spare time enjoys nothing more than lacing up her shoes and hitting the roads and trails (the muddier, the better), usually wearing at least two sports watches.