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1996 Yosemite Valley landslide

Natural landslide

Summary

Natural landslide

Field	Value
title	1996 Yosemite Valley Landslide
image	1996 Yosemite Valley rockslide.jpg
caption	Aftermath of the landslide
date
place	Yosemite Valley, YNP, Mariposa County, CA, United States
coordinates
cause	162,000 tons of debris fell at speeds of up to 160 mph
reported deaths	1

The 1996 Yosemite Valley landslide occurred on July 10, 1996, near the Happy Isles trailhead in Yosemite Valley, Yosemite National Park, Mariposa County, California. 162,000 tons of rocks and other debris fell to the ground at over 160 miles per hour. Of the 12 campers/hikers involved in the incident, one was killed. The landslide competes with the 1997 Merced River flood and the 2013 Rim wildfire for the designation of the worst natural disaster in Yosemite to date. The earthquake caused by the rock slide was followed almost immediately by a sonic boom. Soon afterward a granite dust mushroom cloud formed over Happy Isles. The immense pressure created at the base of the rock slide blew down giant pine trees. Afterwards the nearby campground tables and trees were covered with a thick coat of granite dust.

Impacts

The Yosemite Rock Fall"}}

The first impact occurred at 18:52:28.0 Pacific Daylight Time (02:52:28 UTC), and the second at 18:52:41.6 PDT (02:52:41 UTC).

Effects

One of the impacts killed a hiker near the cliffs.

The force of the impacts was comparable to a 2.15-magnitude earthquake. The impacts also triggered the formation of a massive dust cloud. One witness "noted that the sky went black for six minutes as the dust raised by the cloud blocked out the late afternoon light." The rock fall also caused the uprooting or damage of about 1,000 trees in the immediate blast zone. Structures damaged by the snapping of these trees included the Happy Isles Nature Center, a snack bar, and a bridge. On the day of the incident, the park was hosting as many as 20,000 visitors.

References

[https://web.archive.org/web/20000229125842/http://www.aldha.org/yosemite.htm Appalachian Long Distance Hikers Association. ALDHA Landslide at Yosemite]
Robert Uhrhammer. (December 10, 1996). "The Yosemite Rock Fall of July 10, 1996". berkeley.edu.
(2000). "Unusual July 10, 1996, rock fall at Happy Isles, Yosemite National Park, California". Geological Society of America Bulletin.
Morrissey M. M.. (1999). "Air blasts generated by rockfall impacts: Analysis of the 1996 Happy Isles event in Yosemite National Park". Journal of Geophysical Research: Solid Earth.
Stephen Schwartz & Teresa Moore. (July 11, 1996). "Huge Rock Slide in Yosemite – 1 Killed / Several Injured as slab plunges into Happy Isles area". [[San Francisco Chronicle]].

Wikipedia Source

This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page.

geology-of-yosemite-national-park yosemite-national-park 1996-natural-disasters-in-the-united-states natural-disasters-in-california history-of-mariposa-county,-california landslides-in-the-united-states deaths-in-yosemite-national-park 1990s-landslides 1996-natural-disasters 1996-in-california

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