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Titel |
Investigation and hazard assessment of the 2003 and 2007 Staircase Falls rock falls, Yosemite National Park, California, USA |
VerfasserIn |
G. F. Wieczorek, G. M. Stock, P. Reichenbach, J. B. Snyder, J. W. Borchers, J. W. Godt |
Medientyp |
Artikel
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Sprache |
Englisch
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ISSN |
1561-8633
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Digitales Dokument |
URL |
Erschienen |
In: Natural Hazards and Earth System Science ; 8, no. 3 ; Nr. 8, no. 3 (2008-05-06), S.421-432 |
Datensatznummer |
250005522
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Publikation (Nr.) |
copernicus.org/nhess-8-421-2008.pdf |
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Zusammenfassung |
Since 1857 more than 600 rock falls, rock slides, debris slides, and debris
flows have been documented in Yosemite National Park, with rock falls in
Yosemite Valley representing the majority of the events. On 26 December
2003, a rock fall originating from west of Glacier Point sent approximately
200 m3 of rock debris down a series of joint-controlled ledges to the
floor of Yosemite Valley. The debris impacted talus near the base of
Staircase Falls, producing fragments of flying rock that struck occupied
cabins in Curry Village. Several years later on 9 June 2007, and again on 26
July 2007, smaller rock falls originated from the same source area. The 26
December 2003 event coincided with a severe winter storm and was likely
triggered by precipitation and/or frost wedging, but the 9 June and 26 July
2007 events lack recognizable triggering mechanisms. We investigated the
geologic and hydrologic factors contributing to the Staircase Falls rock
falls, including bedrock lithology, weathering, joint spacing and
orientations, and hydrologic processes affecting slope stability. We
improved upon previous geomorphic assessment of rock-fall hazards, based on
a shadow angle approach, by using STONE, a three-dimensional rock-fall
simulation computer program. STONE produced simulated rock-fall runout
patterns similar to the mapped extent of the 2003 and 2007 events, allowing
us to simulate potential future rock falls from the Staircase Falls
detachment area. Observations of recent rock falls, mapping of rock debris,
and simulations of rock fall runouts beneath the Staircase Falls detachment
area suggest that rock-fall hazard zones extend farther downslope than the
extent previously defined by mapped surface talus deposits. |
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