52 Documented Rock Falls in 2009

In Geology

Recorded rockfalls in Yosemite National Park from 1857-2009. Courtesy NPS.

Most of the time you don’t hear about a rockfall in Yosemite unless it closes a road or hotel or someone is in the wrong spot at the wrong time.

@YosemiteScience posted a link to the great new rockfall page on the NPS website explaining rock falls and how the park addresses them. Of more interesting note, the page also contains rockfall information for 2009 as well as a map of the points rock falls have taken place in the park.

In 2009, there were 52 documented rock falls in Yosemite, with an approximate cumulative volume of 48,120 cubic meters (142,000 tons). The vast majority of this volume was associated with rock falls occurring in March from Ahwiyah Point near Half Dome. The largest of these had an approximate volume of 45,300 cubic meters (about 134,000 tons), making it the largest rock fall in Yosemite Valley in 22 years. The impact of the falling rock generated ground-shaking similar to a magnitude 2.5 earthquake. Other notable 2009 rock falls occurred in August and September from the Rhombus Wall immediately north of the Ahwahnee Hotel, for a cumulative volume of about 1,200 cubic meters (roughly 3,600 tons). (NPS)

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