July 19, 2021 marked the 25th anniversary of the 1996 Happy Isles rockfall in Yosemite National Park. The deadly incident sits as a reminder of the power of nature amidst the massive rock walls of California’s most popular National Park.
At 6:52 pm on July 10, 1996, two blocks with a combined volume of about 30,000 cubic meters and weighing about 90,000 tons broke loose from high on the southeast part of Glacier Point, hitting the valley floor near Happy Isles. In terms of volume, this equates to about 2000 SUVs dropping onto the valley floor at the same time. The impacts of the blocks generated an airblast with wind speeds up to 280 miles per hour, comparable to that of a Category 5 hurricane or a F5 tornado on the Fujita Scale.
The airblast uprooted and snapped about one thousand trees, which damaged buildings and caused one fatality and several serious injuries. Following the airblast, a dense cloud of pulverized rock blanketed the area with coarse sand and dust. Dust rose rapidly into the air and plunged the Happy Isles area into darkness for several minutes. Search and rescue personnel spent the next several days searching for victims in extremely challenging conditions but fortunately discovered no further casualities.
Although tragic, this event would have been much more consequential if the rockfall had occurred just a few hours earlier. Nevertheless, the 1996 Happy Isles rockfalls remains one of the most devastating rockfalls in Yosemite’s history.
The above Helicopter footage shows the destruction of the rockslide showing hundreds of downed trees and rocks on the valley floor. On-the-scene footage of the destruction at Happy Isles is then shown. Emergency search and rescue teams as well as search dogs scour the rubble searching for survivors and clearing the debris. Footage of destroyed building exteriors and interiors are also featured.