It’s been a geology-heavy few days for Yosemite national park this past week, with two separate rock falls crashing to the ground, killing two people and injuring several.
The first occurred on Wednesday, with victim Andrew Foster, 32, from Wales; the second, which was apparently even more massive, on Thursday. Both were near to the famous El Capitan rock formation.
Climber Ryan Sheridan who was there to see both falls commented on the second fall: “It was in the same location of the previous rock fall. A larger rock fall let loose, easily three times the size,” Sheridan said.
The national park tweeted that it would be blocking off a road on the north side of the park; park authorities are telling visitors to use the southern access road.
Although rock falls rarely take lives, they are not actually uncommon. Yosemite experiences approximately 80 rock falls annually; what is uncommon is that those falling rocks hit people. “The rock fall itself is nothing unusual,” Yosemite geologist Greg Stock said. “We have had larger rock falls occur in the valley this year.” (In fact, 7 other falls occurred in the same area within four hours).
He stressed that the fall was not caused by climbers or their gear. More likely, it was due to the expansion and contraction of the granite as it heats up during the summer and gets cold and more brittle in the winter, reports the Guardian. Since 1857, rock falls overall have killed 16 people and injured more than 100.
Authorities estimated that the total rocks that fell weighed about 1,300 tons; the slab that took the biggest crash was roughly 130ft tall and 65ft wide – in other words, a large apartment building. It fell from the “waterfall route” on the east buttress of El Capitan, and released a plume of dust and debris.
“It’s a lot like a lightning strike,” said Alex Honnold, the first person to scale El Capitan (7,569ft) alone and without ropes. “Sometimes geology just happens.”
Sources: The Guardian, National Geographic, The Washington Post
