Rockfall isn’t as rare as it seems
The enormous chunk of granite that broke off the face of El Capitan on Wednesday, killing a climber from Britain and seriously injuring his partner, marked the first rockfall fatality in Yosemite in 18 years, a fact that obscures how frequently the towering cliffs offload their deadly quarry.
The sheet of rock that landed on the two climbers at 1:52 p.m. was the first of seven rockfalls over four hours near Horsetail Fall, just west of the East Buttress of El Capitan, that rained 1,300 tons of debris into the valley and sent up a
giant dust plume, park officials said.
The 130-foot-long, 65-foot-wide flake — between 3 and 10 feet thick — fell 650 feet before slamming into the cliff and breaking into boulders. Park rangers and a rescue team rushed to the scene and found a man and a woman lying at the base of the cliff, where they had apparently been walking as they moved toward or away from the access point for a popular climb known as the Waterfall Route.
“The victims, a couple visiting the park from Great Britain, were in the park to rock-climb but were not climbing at the time of the initial rockfall,” Yosemite spokesman Scott Gediman said. “The male was found deceased, and the female was flown out of the park with serious injuries.”
The man was the first person to die in a rockfall-related accident in Yosemite since climber Peter Terbush was killed on June 13, 1999, as he stood below Glacier Point belaying his partner on a route called Apron Jam. There have been 16 fatalities and more than 100 injuries from rockfalls in Yosemite since 1857, according to the park.
Gediman said the man’s name will not be released until the National Park Service, working through British consular officials, is able to notify his family.
The slab came loose 1,800 feet above the valley floor, about halfway up the granite monolith. It was not a recognized feature on any climbing route, but the accident happened at the height of the Yosemite climbing season, in front of several frightened rock climbers. One man, who was on the wall at the time with two others, told a rock-climbing forum that he watched in horror as “a sheet of rock about 100 feet square” flew by.
Greg Stock, the park geologist, said the slab that initially fell loosened the rock above it, causing smaller chunks to periodically break off throughout the day, with the last one cracking loose around 5:45 p.m.
“What happened was fairly typical for what we call progressive rockfalls,” said Stock, who worked with the U.S. Geological Survey to investigate the exfoliated area by helicopter. “Sometimes that process can go on for days or weeks or even months.”
Stock said a 2009 rockfall on a cliff north of the Ahwahnee Hotel, now known as the Majestic Yosemite Hotel, loosened rock in such a large area that granite continued to tumble down for some 15 months.
The cause of the latest fall is under investigation, but Stock said it probably had something to do with the cold weather last week and warm weather this week. Swings of temperature, water getting into cracks, and ice melting and freezing all cause rock to expand and contract, producing fissures.
Stock said about 80 rockfalls a year are confirmed in Yosemite, with countless others unreported. El Portal Road, near the western entrance to the park, was blocked June 12 by a larger rockfall, though nobody was hurt.
The scariest rockfall may have been one that occurred on the morning of Oct. 8, 2008, when a slab of granite crashed into Curry Village, now known as Half Dome Village, flattening tents, snapping trees and forcing hundreds of campers to run for their lives in underwear and nightclothes as boulders bounced around them like hail.
Miraculously, nobody was killed, but park officials subsequently tore down or relocated more than 230 cabins.
“Just the following year, there was a rockfall in that area, where boulders were falling within the footprint of where cabins were once located,” Stock said.
He said there isn’t much anyone can do when a rockfall happens other than run or take shelter behind the largest boulder available.
“Rockfalls are a common natural process here, and they can happen at any time,” Stock said, “so people should be aware.” Peter Fimrite is a San Francisco Chronicle staff writer. Email: pfimrite@ sfchronicle.com Twitter: @pfimrite