Top-Ten paper at GSA
2017-01-23 | Dr. John Hopkins
On May 25, 2014 the longest landslide in Colorado’s historical record occurred in west-central Colorado, six miles southeast of the small town of Collbran in Mesa County, taking the lives of three local men. The landslide was 2.8 miles long, covered almost a square mile of the West Salt Creek valley and the net volume displacement was 38 million yd3. The fast-moving (40-85 MPH), high-mobility landslide was caused by an initial rotational slide of a half-mile-wide block of Eocene Green River Formation. The resultant rock failures, rockmass disaggregation, and mostly valley-constrained rock avalanche, dropped approximately 2,100 ft in elevation as a rapid series of cascading surges of chaotic rubble composed of fragments of pulverized rock, vegetation, topsoil, and mud. Local seismometers recorded a magnitude 2.8 earthquake from the event with a seismic wave train duration of approximately three minutes. The toe of the landslide came within 200 ft of active gas-production wellheads and loss of irrigation ditches and water impacted local ranches and residents.
The CGS’s Matt Morgan and Jon White were two of the co-authors on one of the top-ten Geological Society of America (GSA) 2016 book chapters and journal articles, this out of 600 papers. The article describes a comprehensive forensic analysis of the massive West Salt Creek rock avalanche that occurred in late May 2014 in western Colorado (USA). The analysis relied on large-scale (1:1000) structural mapping accomplished via high-resolution unmanned aircraft system imagery along with seismic data generated by more than twenty stations within approximately 500 miles (800 km) of the event. The avalanche was the largest mass-movement slope failure in the historical record of Colorado: it killed three people and narrowly avoided destroying a gas wellhead.
This paper was just one of the outcomes of CGS research into the causes of the West Salt Creek landslide. A comprehensive (and also award-winning) report, Bulletin 55 – The West Salt Creek Landslide: A Catastrophic Rockslide and Rock/Debris Avalanche in Mesa County details the entire scope of the geoscience work that the CGS and other agencies did on the catastrophic event.