The 1996

Yosemite Valley Yosemite Valley ( ; ''Yosemite'', Miwok for "killer") is a U-shaped valley, glacial valley in Yosemite National Park in the western Sierra Nevada (U.S.), Sierra Nevada mountains of Central California, United States. The valley is about long a ...

landslide Landslides, also known as landslips, rockslips or rockslides, are several forms of mass wasting that may include a wide range of ground movements, such as rockfalls, mudflows, shallow or deep-seated slope failures and debris flows. Landslides ...

occurred on July 10, 1996, near the

Happy Isles Happy Isles is a group of small isles in the Merced River in Yosemite National Park, California, USA. They are located at the easternmost end of the Yosemite Valley floor. This scenic spot is the starting point for the Mist Trail, and is also ...

trailhead in

Yosemite National Park Yosemite National Park ( ) is a List of national parks of the United States, national park of the United States in California. It is bordered on the southeast by Sierra National Forest and on the northwest by Stanislaus National Forest. The p ...

, Mariposa County,

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

. 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 The January 1997 flood of the Merced River (flooded/flooded from the watershed/floodplain of the Merced River) occurred from December 31, 1996, to January 5, 1997, throughout the Yosemite Valley in Yosemite National Park, Mariposa County, ...

and the 2013 Rim wildfire for the designation of the worst

natural disaster A natural disaster is the very harmful impact on a society or community brought by natural phenomenon or Hazard#Natural hazard, hazard. Some examples of natural hazards include avalanches, droughts, earthquakes, floods, heat waves, landslides ...

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 first impact occurred at 18:52:28.0

Pacific Daylight Time The Pacific Time Zone (PT) is a time zone encompassing parts of western Canada, the western United States, and western Mexico. Places in this zone observe standard time by subtracting eight hours from Coordinated Universal Time ( UTC−08:00). ...

(02:52:28

UTC Coordinated Universal Time (UTC) is the primary time standard globally used to regulate clocks and time. It establishes a reference for the current time, forming the basis for civil time and time zones. UTC facilitates international communica ...

), and the second at 18:52:41.6 PDT (02:52:41 UTC).

Effects

One of the impacts killed a

hiker A hike is a long, vigorous walking, walk, usually on trails or footpaths in the countryside. Walking for pleasure developed in Europe during the eighteenth century. Long hikes as part of a religious pilgrimage have existed for a much longer tim ...

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

{{Yosemite National Park Geology of Yosemite National Park Yosemite National Park 1996 natural disasters in the United States Natural disasters in California History of Mariposa County, California Yosemite Valley landslide 1996 Deaths in Yosemite National Park 1990s landslides 1996 natural disasters 1996 in California

Impacts

Effects

See also

References