Geologists assess Yosemite hotel rockfall risk

YOSEMITE NATIONAL PARK — Scientists worked Thursday to determine if a boulder avalanche that forced the closure of a landmark Yosemite lodge was a one-time event or a precursor of more rockslides to come.

The Ahwahnee Hotel remained closed following a series of landslides Wednesday that peppered the storied building’s parking lot with boulders — one the size of two SUVs.

There were no injuries but three cars were damaged and the area was covered in a thick layer of gray dust, after the rocks tumbled from Royal Arches, a popular climbing route that towers 1,600 feet above the majestic retreat.

The hotel’s 300 guests were immediately evacuated but escorted back to their rooms Wednesday night to collect their belongings, before being put up in hotels outside the park.

“We realize now that the first one may not be the only one. We want to err on the side of safety,” said park spokeswoman Kari Cobb.

A park geologist has been studying the stability of the granite face cut by glaciers and erosion to resemble the arches for which it was named, hoping to determine by Friday afternoon if the hotel can reopen or if the avalanche was a prelude to other rockfalls.

“Yosemite is a wild place,” Cobb said.

Park scientists say rockfalls seem to have accelerated in recent years and are the most significant force affecting the Yosemite Valley — a spectacular natural wonder that receives more than 3 million visitors a year.

Since 1857, at least 535 rockfalls have killed 14 people and injured 62, more than at any other national park. Only in the last few years has the park hired a full-time geologist to assess risk.

Still the park was caught off guard last year when rocks hit 17 cabins in Curry Village and sent 150 youngsters running for their lives. A month later park officials permanently closed the 233 cabins closest to the base of Glacier Point.

Park policy is to treat rockfalls as part of a potentially larger series of events.

“We know now that we can never predict rockfall,” said Cobb. “We can only learn from what we’ve done in the past and move forward. Even though some visitors will be upset, we can only say that safety is our No. 1 concern.”