UTAH GEOLOGICAL SURVEY Volume 45, Number 3 September 2013 FIRE-RELATED DEBRIS-FLOW HAZARD ON THE WASATCH PLATEAU percent of U.S. copper costs largely due to the disruption to railroad production each year, business1. In today’s dollars, this amounts to and also produces about $700 million. That landslide was esti- The Director’s significant amounts mated at 50 million tons and was just over a Damaging Debris Flows Prompt of molybdenum, gold, mile in length. Kennecott has not stated what Perspective and silver. the cost of returning the mine to full produc- tion will be, but some mineral analysts have Landslide Inventory Mapping Various blogs and speculated that it will be at least $1 billion; if by ichard G. llis press reports have R A so, this event will earn the dubious title as the subsequently commented that the Bingham The hazards theme of this Survey Notes issue nation's most costly landslide. for the 2012 Seeley Fire, Carbon Mine slide is probably one of the largest is a reminder that we live in a geologically human-caused landslides in the world, and These two landslides highlight how the hazardous state. The hazards that concern us Kennecott has suggested it is probably one of costs and impacts of large hazard events can vary from infrequent, large magnitude events the largest mining-related slides. Up to now, rapidly escalate. The paleoseismic record from and Emery Counties, Utah such as major earthquakes to smaller mag- the 1983 Thistle landslide in central Utah has trenches across the Wasatch fault demonstrates nitude, frequent events such as debris flows, by Richard Giraud and Greg McDonald been known as this nation’s most costly land- that magnitude 7 earthquakes recur on average rock falls, and landslides. This spring, a major slide, with $200 million in direct reconstruc- about every 300 years somewhere along failure occurred in the sidewall of Kennecott’s tion costs, and over $100 million in indirect the fault. In addition to many lives lost and open-pit Bingham Canyon Mine. The result- collapsed buildings, the reconstruction costs ing landslide flowed into the pit; the total from such an earthquake are expected be distance between the main scarp and the toe in the range of $10–30 billion (refer to was 1.5 miles. Within days, Kennecott had “Director’s Perspective” in the May 2013 issue posted high-resolution photos of the slide of Survey Notes). on the web, and provided some details about the scale of the slide. The mass of rock in 1“Flooding and Landslides in Utah: An Economic the slide was estimated at 165 million tons, Impact Analysis” Report by Bureau of Economic and equivalent to about 100 million cubic yards of Business Research, University of Utah, December 1984. rubble. Unusual deformation in the pit wall had been monitored for several months prior to the landslide, and Kennecott had moved equipment out of the likely path of the Utah Department of Transportation snow plow clearing the July 7, 2012, fire-related debris flow deposit impending slide. Even so, twelve 330-ton from State Route 31 in Huntington Canyon (photo courtesy of Emery County Sheriff ’s Department). haul-trucks that were parked on a far-side bench several hundred feet above the bottom The 2012 Seeley fire was a lightning-caused fire that on steep, burned slopes. Debris flows are mixtures of water and of the pit were engulfed by the slide (visible burned 75 square miles (48,050 acres) on the Wasatch in photo at the toe of the slide). Kennecott sediment, and in the Seeley fire area, the sediment consists of Plateau in central Utah. The fire, which started on June has stated that production from the mine boulders, gravel, sand, mud, burned tree trunks, partially burned this year could be halved compared to 26 and was contained on July 18, was approximately 15 organic matter, and ash. Some flows contain more water than past years. The mine produces about 25 miles northwest of Huntington and about 12 miles east of sediment and are fluid, having a consistency similar to a dilute Bingham Canyon Mine landslide. Photo courtesy of Thistle landslide, 1983. Kennecott Utah Copper. Fairview. Thunderstorm rainfall on July 7, 2012, produced milkshake. Other flows contain more sediment than water and fire-related debris flows and flooding, causing damage to are more viscous, having a consistency similar to wet concrete. Editorial Staff Vicky Clarke State Route (SR) 31 and Huntington Creek in Huntington Fire-related debris flows occur when wildfires leave bare ground State of Utah Contents Lori Steadman, Stevie Emerson, Energy and Minerals David Tabet Canyon. Additional thunderstorm rainfall in 2012 produced and little vegetation to intercept intense thunderstorm rainfall, Gary R. Herbert, Governor Nikki Simon, Jay Hill Robert Blackett, Craig Morgan, Damaging Debris Flows Prompt Landslide Jeff Quick, Taylor Boden, increasing surface-water runoff. The runoff water concentrates in Department of Natural Resources debris flows and flooding on July 16, July 30, July 31, and Geologic Hazards Steve Bowman Thomas Chidsey, Cheryl Gustin, Inventory Mapping for the 2012 Seely Fire, Michael Styler, Executive Director September 1, 2012. To date in 2013, rainfall produced stream channels where it erodes and incorporates loose channel Carbon and Emery Counties, Utah .............1 Richard Giraud, William Lund, Tom Dempster, Brigitte Hucka, UGS Board Greg McDonald, Jessica Castleton, Stephanie Carney, Ken Krahulec, debris flows and flooding on July 16 and 18. These rain- sediment to form debris flows. The debris flows continue to erode Rock Fall: An Increasing Hazard in Urbanizing Mark Bunnell, Chair Gregg Beukelman, Chris DuRoss, Brad Wolverton, Sonja Heuscher, storms show how prone the steep, burned slopes are to channel sediment and increase in volume as they flow down steep Southwestern Utah ....................................4 William Loughlin, Tom Tripp, Tyler Knudsen, Corey Unger, Mike Vanden Berg, Andrew Rupke, mountain channels until they reach an alluvial fan at the channel Sunny Dent, Kenneth Puchlik, Adam McKean, Ben Erickson, Mark Gwynn, Christian Hardwick, generating debris flows and flooding. New Geologic Data Resources for Utah ..........6 Marc Eckels, Pete Kilbourne, Pam Perri, Adam Hiscock Peter Nielsen, Hobie Willis, mouth and spread out, depositing sediment. Energy News .................................................... 8 Kevin Carter (Trust Lands Rebekah Wood Administration-ex officio) Geologic Information and Outreach The Utah Geological Survey (UGS) and the Manti–La Sal Debris flows are one of the most dangerous post-fire hazards Teacher's Corner ..............................................9 Sandra Eldredge Groundwater and Paleontology National Forest (MLSNF) modified an existing cost-share because they can be life threatening, move rapidly, and strike with Glad You Asked .............................................. 10 UGS Staff Christine Wilkerson, Patricia Stokes, Mike Lowe Mark Milligan, Lance Weaver, James Kirkland, Janae Wallace, agreement to focus on landslide inventory mapping of the little warning. Debris flows are generally more damaging than GeoSights .......................................................12 Administration Gentry Hammerschmid, Jim Davis, Martha Hayden, Hugh Hurlow, Seeley fire burn area. The map and accompanying geographic water floods because of their destructive power. Debris-flow den- Survey News ...................................................13 Richard G. Allis, Director Marshall Robinson, Bryan Butler, Don DeBlieux, Kim Nay, information system (GIS) geodatabase show and characterize Kimm Harty, Deputy Director Robyn Keeling Paul Inkenbrandt, Lucy Jordan, sity, thickness, and velocity can combine to produce large impact New Publications ..............................back cover Starr Soliz, Secretary/Receptionist Kevin Thomas, Walid Sabbah, landslides (including debris flows) within the burn area to provide pressures, and flows can destroy buildings, campgrounds, roads, Geologic Mapping Grant Willis Dianne Davis, Administrative Secretary Rich Emerson, Stefan Kirby, information to manage potential post-fire landslides and to bridges, culverts, and other infrastructure in their path. Thirteen Kathi Galusha, Financial Manager Jon King, Douglas Sprinkel, Design: Nikki Simon Scott Madsen, Jennifer Jones, prioritize areas where risk-reduction measures are needed. Linda Bennett, Accounting Technician Kent Brown, Basia Matyjasik, Diane Menuz of Utah’s fifteen debris-flow fatalities occurred in campgrounds at Cover: September 1, 2012, fire-related debris flow deposit on Michael Hylland, Technical Reviewer Donald Clark, Bob Biek, Debris flows are the most common type of landslide following a night, where fast-moving debris flows struck with little warning the Mill Canyon alluvial fan following the 2012 Seeley fire. Robert Ressetar, Technical Reviewer Paul Kuehne, Zach Anderson Photo by Richard Giraud. wildfire and are triggered when intense thunderstorm rain falls and left victims with no time to move to a safe location. The UGS Survey Notes is published three times yearly by Utah Geological Survey, 1594 W. North Temple, Suite 3110, Salt Lake City, Utah 84116; (801) 537-3300. The Utah Geological Survey provides timely scientific information about Utah’s geologic environment, resources, and hazards. The UGS is a division of the Department of Natural Resources. Single copies of Survey Notes are distributed free of SEPTEMBER 2013 1 charge within the United States and reproduction is encouraged with recognition