2019 Cable Mountain Rockfall, Zion National Park, Utah

On August 24, 2019, at approximately 5:30 p.m., a large slab of Navajo Sandstone detached from a vertical cliff face of Cable Mountain above the Weeping Rock area, in Zion National Park, Utah. The slab of rock detached approximately 2000 vertical feet (610 meters) above the parking lot at the Weeping Rock trailhead. Utah Geological Survey (UGS) geologists conducted a site reconnaissance on August 26, 2019. An additional investigation including high-resolution photo-graphs and video collected using a small unmanned aircraft system (sUAS), was conducted October 24–25, 2019. Data were also collected to help assess the stability of a prolific rockfall area that has repeatedly damaged the nearby Hidden Canyon trail. The sUAS data collected were used to create a digital elevation model (DEM), structure from motion (Sf M) model, and an orthomosaic image of a large part of the western Cable Mountain, Weeping Rock, and Hidden Canyon areas. The estimated volume of the rock avalanche was calculated to be 435,712 cubic feet (12,338 m3). The rock mass was approximately 31,000 tons. The calculated volume and flow-like qualities of the event classify it as a very small rock avalanche. No specific triggering event could be identified for the rock avalanche event; however, it appears thermal cycling is a likely contributing factor. The recommended solution in this situation is (1) avoidance of the rockfall hazard, such as not building structures and limiting access in areas with frequent rockfall and/or (2) acceptance of the hazard and the risk associated with it, knowing that the consequences of this option could result in loss of life and damage to property.

[
  "000:00"
]

{
  "fn": "OpenTopography Support",
  "@type": "vcard:Contact",
  "hasEmail": "mailto:info@opentopography.org"
}

[
  {
    "@type": "dcat:Distribution",
    "title": "OpenTopography Data Download Page",
    "accessURL": "https://doi.org/10.5069/G9VT1Q8M",
    "mediaType": "text/html"
  }
]

[
  "Utah",
  "Washington County",
  "Zion National Park",
  "community-dataspace",
  "rockfall",
  "sfm"
]

[
  "000:000"
]

{
  "name": "OpenTopography",
  "@type": "org:Organization"
}