Rock-fall hazards in the Yosemite Valley

1998 ◽  
Author(s):  
G.F. Wieczorek ◽  
M.M. Morrissey ◽  
Giulio Iovine ◽  
J.W. Godt
Keyword(s):  
Rock Fall ◽  
Yosemite Valley

Rock-fall potential in the Yosemite Valley, California

1999 ◽  
Author(s):  
Gerald F. Wieczorek ◽  
Meghan M. Morrissey ◽  
Giulio Iovine ◽  
Jonathan Godt
Keyword(s):  
Rock Fall ◽  
Yosemite Valley

Supporting Evidence for a 9.6   1 ka Rock Fall Originating from Glacier Point in Yosemite Valley, California

2013 ◽  
Vol 19 (4) ◽  
pp. 345-361 ◽  
Author(s):  
S. E. Cordes ◽  
G. M. Stock ◽  
B. E. Schwab ◽  
A. F. Glazner
Keyword(s):  
Rock Fall ◽  
Supporting Evidence ◽  
Yosemite Valley

scholarly journals Investigation and hazard assessment of the 2003 and 2007 Staircase Falls rock falls, Yosemite National Park, California, USA

2008 ◽  
Vol 8 (3) ◽  
pp. 421-432 ◽  
Author(s):  
G. F. Wieczorek ◽  
G. M. Stock ◽  
P. Reichenbach ◽  
J. B. Snyder ◽  
J. W. Borchers ◽  
...  
Keyword(s):  
National Park ◽  
Three Dimensional ◽  
Source Area ◽  
Rock Fall ◽  
Yosemite National Park ◽  
Rock Falls ◽  
Joint Spacing ◽  
Hydrologic Processes ◽  
Yosemite Valley ◽  
Triggering Mechanisms

Abstract. 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.

scholarly journals Rockfall hazard and risk assessment in the Yosemite Valley, California, USA

2003 ◽  
Vol 3 (6) ◽  
pp. 491-503 ◽  
Author(s):  
F. Guzzetti ◽  
P. Reichenbach ◽  
G. F. Wieczorek
Keyword(s):  
Friction Coefficient ◽  
Computer Program ◽  
Rolling Friction ◽  
Rock Fall ◽  
Flying Height ◽  
Rock Falls ◽  
Slope Movements ◽  
Yosemite Valley ◽  
Rolling Friction Coefficient ◽  
Rock Slides

Abstract. Rock slides and rock falls are the most frequent types of slope movements in Yosemite National Park, California. In historical time (1857–2002) 392 rock falls and rock slides have been documented in the valley, and some of them have been mapped in detail. We present the results of an attempt to assess rock fall hazards in the Yosemite Valley. Spatial and temporal aspects of rock falls hazard are considered. A detailed inventory of slope movements covering the 145-year period from 1857 to 2002 is used to determine the frequency-volume statistics of rock falls and to estimate the annual frequency of rock falls, providing the temporal component of rock fall hazard. The extent of the areas potentially subject to rock fall hazards in the Yosemite Valley were obtained using STONE, a physically-based rock fall simulation computer program. The software computes 3-dimensional rock fall trajectories starting from a digital elevation model (DEM), the location of rock fall release points, and maps of the dynamic rolling friction coefficient and of the coefficients of normal and tangential energy restitution. For each DEM cell the software calculates the number of rock falls passing through the cell, the maximum rock fall velocity and the maximum flying height. For the Yosemite Valley, a DEM with a ground resolution of 10 × 10 m was prepared using topographic contour lines from the U.S. Geological Survey 1:24 000-scale maps. Rock fall release points were identified as DEM cells having a slope steeper than 60°, an assumption based on the location of historical rock falls. Maps of the normal and tangential energy restitution coefficients and of the rolling friction coefficient were produced from a surficial geologic map. The availability of historical rock falls mapped in detail allowed us to check the computer program performance and to calibrate the model parameters. Visual and statistical comparison of the model results with the mapped rock falls confirmed the accuracy of the model. The model results are compared with a previous map of rockfall talus and with a geomorphic assessment of rock fall hazard based on potential energy referred to as a shadow angle approach, recently completed for the Yosemite Valley. The model results are then used to identify the roads and trails more subject to rock fall hazard. Of the 166.5 km of roads and trails in the Yosemite Valley 31.2% were found to be potentially subject to rock fall hazard, of which 14% are subject to very high hazard.

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