Six hikers were caught in a collapse at the Big Four Ice Caves on July 7, leaving one dead and five injured. The body of the deceased has not been identified or recovered because of dangerous search-and-rescue conditions, according to the Seattle Times. The three adults and two children who were among those injured were hospitalized, and one remains in intensive care.
The Big Four Ice Caves, which are now closed indefinitely, are located east of Seattle, Washington at the base of Big Four Mountain in the Mount Baker-Snoqualmie National Forest, where avalanches during winter months pack enough snow to maintain the structure of the caves. However, warmer temperatures this year increased snowmelt and made the ice caves unstable. Snohomish County Sheriff’s Office spokesperson Shari Ireton spoke to reporters after the collapse, describing the state of the structures and their potential dangers. "There was a large pile of ice and rock that came down,” said Ireton. “In many ways, it was similar to an avalanche. The heat has weakened the caves themselves and they are essentially a frozen-over avalanche chute sitting over a waterfall sitting below a giant rock chute. It’s incredibly dangerous.”
The caves are under the jurisdiction of the U.S. Forest Service, and just like other potentially dangerous natural structures in national forests and parks (like the top of Half Dome and the cliffs of the Grand Canyon), local authorities aren't always able to monitor and regulate access and safety. Because of this, it's important that you take the necessary precautions to stay safe when exploring ice caves across the country. "The most important thing is to have situational awareness," says Chris Smith, chief of protection at Apostle Islands National Park, which boasts ice caves along Lake Superior's southern shore. "Know where you are, assess risks, and take action accordingly. If you are visiting ice caves on a 40-degree day, if there is minimal cloud cover or wind, if the caves or dripping, or if you see small cracks you need to identify those factors and act mindfully."
Smith says that ice can never be completely trusted, and that it's best to steer clear of going into any structure that is freestanding or unsupported by cliffs, rocks, or another substance besides ice and snow (such as the Big Four Ice Caves). The ice caves in the Apostle Islands are not freestanding frozen structures, but ice-covered caves. Therefore, the "stability comes from the quality and quantity of the ratio of cliff to ice," making them more stable. But that doesn't mean that a small crack on a negative 20-degree day won't result in an icefall. Because of the variations in each structure, it's best to check park directories, ice lines, and park Facebook pages for updates about structure conditions to educate yourself on the current situation of where you are visiting. As for when you are at the caves, Smith says that it's always necessary to "look up, look down, look all around" and to leave any ice structure that has cracks, is dripping, or if you hear a boom or crash, as these are signs of collapse.