Unusual July 10, 1996, rock fall at Happy Isles, Yosemite National Park, California

Wieczorek, Gerald F.; Snyder, James B.; Waitt, Richard B.; Morrissey, Meghan M.; Uhrhammer, Robert A.; Harp, Edwin L.; Norris, Robert D.; Bursik, Marcus; Finewood, Lee G.

doi:10.1130/0016-7606(2000)112<75:ujrfah>2.0.co;2

Cited by 70 publications

(31 citation statements)

References 3 publications

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“…The rock fall impact was detected widely on strong motion seismic networks as far away as 350 km, registering as a magnitude 2Á4 earthquake. This is only the second rock fall in Yosemite National Park that was assigned a seismic event identification number in the California strong motion seismic network earthquake record (the first was the 1996 Happy Isles rock fall; Uhrhammer, 1996;Wieczorek et al, 2000), a testament to the size and energy generated from this event.…”

Section: The 2009 Ahwiyah Point Rock Fallmentioning

confidence: 99%

“…The history of rock falls, rock-fall triggering, and assessment of rock-fall hazards in Yosemite has been extensively studied (e.g. Wieczorek et al, 1995Wieczorek et al, , 1998Wieczorek et al, , 2000Wieczorek et al, , 2008Wieczorek and Jäger, 1996;Wieczorek andSnyder, 1999, 2004;Wieczorek, 2002;Guzzetti et al, 2003;Stock and Uhrhammer, 2010). Because Yosemite Valley experiences a high frequency of rock falls contained in a small geographic area, it represents an ideal laboratory for closely monitoring rock fall activity.…”

Section: Geologic Setting and Rock Fall Triggering Mechanismsmentioning

confidence: 99%

“…Rock falls and rockslides have been detected in several cases by strong motion seismic networks that recorded impacts from these events (Uhrhammer, 1996;Wieczorek et al, 2000;Deparis et al, 2008;Dammeier et al, 2011). Seismic stations as far as 200 km away recorded the 10 July 1996 Happy Isles rock fall in Yosemite Valley.…”

Section: Seismic Monitoring Of Rock Fallsmentioning

confidence: 99%

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Rock fall dynamics and deposition: an integrated analysis of the 2009 Ahwiyah Point rock fall, Yosemite National Park, USA

Zimmer

Collins

Stock

et al. 2012

Earth Surf Processes Landf

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We analyzed a combination of airborne and terrestrial LiDAR, high‐resolution photography, seismic, and acoustic data in order to gain insights into the initiation, dynamics, and talus deposition of a complex rock fall. A large (46 700 m3) rock fall originated from near Ahwiyah Point in eastern Yosemite Valley and fell a total of 730 m to the valley floor on 28 March 2009. Analyses of remote sensing, seismic, and acoustic data were integrated to reconstruct the rock fall, which consisted of (1) the triggering of a 25 400 m3 rock block in an area of intersecting and sometimes highly weathered joint planes, (2) the sliding and subsequent ballistic trajectory of the block from a steeply dipping ledge, (3) dislodging of additional rock from the cliff surface from beneath the rock fall source area, (4) a mid‐cliff ledge impact that detached a volume of rock nearly equivalent in volume to the initial block, (5) sliding of the deteriorating rock mass down the remainder of the cliff, and (6) final impact at the base of the cliff that remobilized the existing talus downward and outward and produced an airblast that knocked down hundreds of trees. The depositional geomorphology indicates that the porosity of the fresh talus is significantly lower than that expected for typical blocky talus slopes, likely because the rock debris from this event was pulverized into smaller, more poorly sorted fragments and densified via dynamic compaction when compared to less energetic, fragmental‐type rock falls. These results suggest that accumulation of individual rock‐fall boulders tends to steepen talus slopes, whereas large, energetic rock falls tend to flatten them. Detachment and impact signals were recorded by seismic and acoustic instruments and highlight the potential use of this type of instrumentation for generalized rock fall monitoring, while LiDAR and photography data were able to quantify the cliff geometry, rock fall volume, source and impact locations, and geomorphological changes to the cliff and talus. Published in 2012. This article is a US Government work and is in the public domain in the USA.

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Section: The 2009 Ahwiyah Point Rock Fallmentioning

confidence: 99%

Section: Geologic Setting and Rock Fall Triggering Mechanismsmentioning

confidence: 99%

Section: Seismic Monitoring Of Rock Fallsmentioning

confidence: 99%

See 1 more Smart Citation

Rock fall dynamics and deposition: an integrated analysis of the 2009 Ahwiyah Point rock fall, Yosemite National Park, USA

Zimmer

Collins

Stock

et al. 2012

Earth Surf Processes Landf

View full text Add to dashboard Cite

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“…Also it was assumed that there is no deformation of the tree trunk. Advanced research also consider the influence by the destruction of trunks, branches and leaves at best pained with accumulation of fundamental data (Wieczorek, 2000). Figure 8 shows the flowchart of the complete simulation used in this study.…”

Section: Numerical Modelingmentioning

confidence: 99%

Basic rockfall simulation with consideration of vegetation and application to protection measure

Masuya

Amanuma

Nishikawa

et al. 2009

Nat. Hazards Earth Syst. Sci.

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Abstract. The estimation of risk due to rockfall is often done empirically. As a rational and effective method towards performance-based design of protection measures, a threedimensional simulation method helps to describe the motion of rockfall on a slope and to consider the effect of vegetation probabilistically. This document details a typical simulation method and analyses the manner of rockfalls paired with interference of vegetation and other factors. As application, an actual slope is analyzed where rockfall occurred during the Noto Peninsula Earthquake. Finally, the validity and the benefits of the shown method are the basis for a hazard mapping for rockfall and the planning of measures.

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“…People living on the slope opposite the Pozzole basin stated that "the trees were swept off the ground" by the shock wave of air pushed forward by the moving mass. Air blasts causing a similar effect proceeded some large, rapidly-moving rock falls (Wieczorek et al, 2000).…”

Section: The Mudflow Along the Stava Valleymentioning

confidence: 99%

The Stava mudflow of 19 July 1985 (Northern Italy): a disaster that effective regulation might have prevented

Luino

Graff

2012

Nat. Hazards Earth Syst. Sci.

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Abstract. The disaster occurring in the Eastern Italian Alps in the summer of 1985 was caused by the failure of two tailings dams located just upstream from the village of Stava in the municipality of Tesero (Trento province, Italy). The structure comprised two small storage basins for the deposition of tailings from the separation process of the Prestavel fluorite mine. On their downstream sides, the basins were contained by steep earth embankments, whereas upstream they rested directly on the natural slope. The total height from the base of the lower dam to the crest of the upper dam was over 50 m.On 19 July 1985, the front of the upper dam suddenly burst, triggering a vast mudflow (180 000 m 3 ) that flowed down-channel through Stava, a small village of 20 buildings. The mudflow rapidly traveled over 4.2 km along the Stava Valley and passed through Tesero, before flowing into the Avisio River. The mudflow destroyed many buildings and resulted in 268 fatalities and 20 injuries. From an analysis of the data collected and field observation, several factors may be cited as having contributed to increasing instability, as the upper dam continued to be raised until the disastrous collapse of 19 July. Foremost among these factors is the mistaken assumption that the tailings deposited in the impoundments would consolidate fairly quickly. Indeed, no monitoring system was ever installed to verify the assumed consolidation. Other operational shortcomings and construction errors were contributing factors. Regulations requiring construction standards, operational monitoring, and independent periodic inspection could have prevented this disaster. Comprehensive legislation is required to effectively limit the adverse consequences of tailings dam failures by providing a regulatory environment where the safety and welfare of the local area can be balanced with the economic benefits of mining operations.

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Unusual July 10, 1996, rock fall at Happy Isles, Yosemite National Park, California

Cited by 70 publications

References 3 publications

Rock fall dynamics and deposition: an integrated analysis of the 2009 Ahwiyah Point rock fall, Yosemite National Park, USA

Rock fall dynamics and deposition: an integrated analysis of the 2009 Ahwiyah Point rock fall, Yosemite National Park, USA

Basic rockfall simulation with consideration of vegetation and application to protection measure

The Stava mudflow of 19 July 1985 (Northern Italy): a disaster that effective regulation might have prevented

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