Geologic Hazards in Kentucky: Tools and Methodologies to Further Hazard Assessment
William Andrews and Matt Crawford
2018 KAMM Regional Training May 15, 2018 Outline
• KGS
• Karst Basics • Radon Data/Examples • Landslides • Earthquakes Tools for Hazard Assessment • Summary MISSION: To investigate mineral, energy and water resources, and geologic hazards of Kentucky, focusing on research in earth resources and processes, public service, and the dissemination of our data, knowledge, and experience to stakeholders in industry, government, educational institutions, and the general public. Data Geologic Mapping
• KGS has complete, detailed, digital geologic mapping for the state
• 1968-78 USGS-KGS joint program
• Can produce derivative applications for various hazards LiDAR – Light Detection and Ranging
• High resolution elevation data • Laser pulses hitting the earth at random x, y, z points (location and elevation point cloud) • Multiple returns for one pulse get filtered out non-ground hits, creating a bare-earth model • 1.4 m H resolution and ability to create 2 ft. contours is typical
Geologic hazards management and mitigation? Primary role is geologic hazard delineation, evaluation, and assessment focusing on the geologic potential and geologic processes
• Active programs/example projects Geologic Hazards & Engineering Geology Earthquakes Landslides Sinkhole Mapping/Groundwater Investigations Radon Geologic Mapping
• Potential opportunities & collaboration Geologic Hazards
3 main elements to communicating geologic hazards (From the Landslide Handbook by Highland and Bobrowsky, 2008)
1. Potential of an event of a size and location that would cause damage, disrupt a standard of safety, or result in causalities
2. Expected location and extent of effects on ground and buildings
3. Severity of the effects on the ground and structures
Key: How to make this information useful? • State Hazard Mitigation Plan Update 2018
• KGS conducting hazard and risk assessment for earthquakes, landslides, karst, & mine subsidence Karst & Groundwater
Derived from a Slavic word meaning “barren, stony ground,” the term karst describes a landscape (terrain), a geologic setting (terrane), and a type of aquifer (or hydrology) characterized by features formed by the dissolution of soluble bedrock:
Approximately 20% of the conterminous United States and 50 percent of the U.S. east of the Mississippi River is underlain by soluble and potentially karstic bedrock About 40% of groundwater used for drinking water in the U.S. comes from karst aquifers According to the Kentucky Division of Water, springs and wells in karst areas supply water to tens of thousands of private homes, and are also used by five public water suppliers serving more than 164,000 citizens in total Comparison of typical surface and subsurface karst features in the Inner Bluegrass (a) and Western Kentucky Pennyroyal (b) Karst Hazards
• Sinkhole flooding
• Dam construction/maintenance
• Groundwater & Surface-water contamination Sinkholes • A form of subsidence that are physically manifested as closed and internally drained topographic depressions, of generally circular shape, that develop where soil subsides or collapses into subsurface voids • Sinkholes can form as a result of both natural (karst-related) processes and as a direct or indirect consequence of human activities • 2 broad categories: subsidence (depression) and collapse • Best estimates indicate that annual costs related to sinkhole damage nationwide range from $125 to $300 million per year (Kuniansky and others, 2016) Karst potential map Karst projects: Using LiDAR to map sinkholes
Floyds Fork – portions of Jefferson, Bullitt, Oldham, and Shelby Counties Karst/Sinkhole Profile Risk Extent Approximately 55 to 60 percent of the state, as indicated by areas underlain by carbonate bedrock and mapped Karst Potential Index1. Potential Hazard Impacts Minor to severe structural damage to buildings; increased building or landscape repair and maintenance costs, decreased property values; damage to pipelines and other above- or below-ground utility infrastructure; seepage and underflow, structural undermining, and potential failure of dams on streams in karst areas; sinkhole and other karst-related flooding; groundwater or surface-water contamination in the event of a chemical spill or release, with the potential to affect private and public water supplies. Period of Occurrence Sinkholes only: At any time. Number of Events in Sinkholes only: 101,632 mapped sinkhole depressions2; 354 documented Kentucky cover-collapse sinkholes (1997–2017)3 Annual Rate of Sinkholes only: Unknown; insufficient data available. Occurrence Warning Time Sinkholes: Often cannot be determined; formation of subsidence sinkholes may provide early warning signs; cover-collapse sinkholes may or may not. Recorded Losses Not documented. Annualized Loss Undetermined, but estimated at $20–$24 million4. 0.25 × (karst area percentage) + 0.75 × (sinkhole area percentage)
• Increase weight for sinkhole area percentage • Combined with sinkhole density Radon Knowing rock and soil types at a site helps determine its radon potential Example mapping projects: Radon
Statewide radon data Detailed geologic map
Statewide radon potential Landslides
Failure of sloping earth materials: Stresses > slope material strength
Forces/stress geology – gravity soils These forces act over time and space at different scales, creating – pore-water pressures slope processes of landslides that can be – slope modification morphology/angle hydrology separated as “causes” and – earthquakes slope development “triggers” Landslide Types: Velocity and Material
From USGS Fact Sheet 2004-3072
Creep Translational Rotational Slide (Slump) Slide
Rockfall Debris Flow (Topple)
Debris Avalanche
Earth Flow Lateral Spread Impact • In the U.S. responsible for $2-3 billion in damages (rivaling annual flood losses) and 25-50 deaths annually
• No systematic catalog of occurrence or impact maintained in U.S. • Damage is poorly documented, considered part of another triggering event (flood, earthquake, tropical storm) • We don’t plan for landslides like we do floods or earthquakes • No insurance plans exist • Hazard assessment is difficult • No standard model for hazard assessment. No earthquake model. • Quantifying risk and loss reduction strategies are different for different types of landslides (variability in site conditions and slide behavior)
• USGS Landslides Hazards Program is funded ~3.5 million/year
• Congresswoman Delbene (WA) introduced a bill “National Landslide Preparedness Act” (H.R. 1675, pending) Impact
• Annual flood costs = $8.4 million • ~$11.2 million was spent on KY EM and FEMA landslide mitigation projects for private residences from 2003 to 2015 • KYTC incurs direct costs of approximately $20 million annually for landslides that damage roads • Annual landslide direct costs = ~$10-20 million
Hickman Co.
Breathitt Co. Landslide Inventory & Information Map
• Known landslide locations from various sources including published maps, reports, field investigations, media alerts, government agencies, & the public • Areas susceptible to debris flows • Landslides located from LiDAR and aerial photography Landslide Inventory & Information Map
Customizable with other GIS layers and tabular data sets Landslide attributes Source desc SourceID County Quad Latitude83 Longitude83 Route Date Observed Failure Date Field Checked Material Failure Type Track Length Width Head scarp height Slip surface depth Geomorphic position Bedrock Formation Failure location Contributing factor Damage Comments Mapping Landslides Using LiDAR
Allows for mapping of features that otherwise would not be possible
LiDAR-derived hillshade and contours Aerial imagery of the same area (2ft). Mapped landslide measures ~200’ across and ~250’ in downslope direction Mapping Landslides Using LiDAR
• Developed a methodology using LiDAR data to document landslides in Kenton and Campbell Counties
• Grant from the USGS Landslides Hazards Program
• 230 potential landslide extents digitized (polygons)
• Mapping preexisting landslides is an indication of areas susceptible to future slope failure Mapping Landslides Using LiDAR Floyd County, Ky.
Hollow fill
Landslides Landslide Susceptibility
(geology reclass value × 0.30) + (slope reclass value × 0.70) = landslide susceptibility Landslide Susceptibility
KYTC Maintenance Costs
• Divided costs into 1-mile segments which were assigned a geologic formation
• Assess the most costly areas and most frequently repaired segments Landslide susceptibility
• Prestonsburg 7.5-min quadrangle
• Model landslide susceptibility using geology, geotechnical parameters, and a LiDAR-based DEM
• Probability that the FS is < 1 for each cell 0.0 – 0.25 • Protocol for statewide effort? 0.25 – 0.50 0.50 – 0.75
Chapella et al (2018, AEG) 0.75 – 1.0 Field Investigations
• Monitoring rainfall, soil moisture, and movement
• Developing long-term hydrologic relationships related to soil shear strength
0.60 70 Near-saturated 400 Drying Near-saturated Above Rd - 70 cm 0.50 60 350 SWEC Strength Model data 50 300 0.40 Drying
Missing 40 250 0.30 30 200
0.20 (mm) Rainfall
20 150 Volumetric Water Content Water Volumetric
0.10 10 (kPa)Shear Strength 100
0.00 0 50 0 0 0.02 0.04 0.06 0.08 Electrical Conductivity (dS/m) Rainfall (mm) 25 cm 44 cm Modeling: Geophysics
Electrical Resistivity (ER)
Geophysical method that injects electric current into the ground Resistance: R= V/i through two electrodes. The resulting Resistivity: ρ=R(A/l) potential is measured between two other electrodes and analyzed in 2D Electrode configuration dictates resolution and depth or 3D modeled images
Goal: Understand the pattern of current (i) distribution (ΔV between 2 pts.) in subsurface and interpret materials • Underutilized geophysics tool
• Fast, repeatable, non-intrusive
• Determination of moisture content, depth-to-bedrock, failure zones, slide geometry, and rock/soil type over a large area Earthquakes
• An earthquake occurs when a fault suddenly ruptures and releases elastic energy in the form of seismic waves
• Earthquakes occur when two blocks of the earth suddenly slip past one another. The surface upon which they slip is called a fault
• Rupture begins at the hypocenter (referred to as the epicenter at the surface)
Earthquakes in and around Kentucky Potential earthquake impacts
Date Location Magnitude Notes 1980 Sharpsburg 5.2 Significant damage in Maysville 1988 Bath County 4.6 Shaking was felt in the area 2003 Bardwell 4.0 Some minor damage in Bardwell 2012 Perry County 4.2 Some minor damage in Letcher and Perry Counties 1980 Sharpsburg earthquake ($3M damages in Maysville)
Peak ground acceleration on rock from a scenario earthquake of magnitude 7.5 in the central New Madrid Seismic Zone Potential ground-motion amplification hazard in Kentucky. The National Earthquake Hazards Reduction Program has classified this hazard for the United States. The moderate amplification potential shown on this figure is equivalent to NEHRP site class D; low amplification potential is equivalent to NEHRP site class C; nil amplification potential is equivalent to NEHRP site classes A or B Scenario Time Level 1 Level 2 Level 3 Level 4 2 a.m. 354 61 6 11 New Madrid I 2 p.m. 700 131 16 28 5 p.m. 652 124 31 26 2 a.m. 1,969 465 48 88 New Madrid II 2 p.m. 6,992 1,917 273 517 5 p.m. 7,016 1,910 313 488 2 a.m. 76 10 1 2 New Madrid III 2 p.m. 157 23 2 4 5 p.m. 153 23 5 4 2 a.m. 492 74 7 13 Wabash 2 p.m. 903 154 17 31 Valley 5 p.m. 681 119 28 24 2 a.m. 1 0 0 0 Sharpsburg 2 p.m. 1 0 0 0 5 p.m. 1 0 0 0 Level 1: Injuries will require medical attention, but hospitalization is not needed Level 2: Injuries will require hospitalization, but are not considered life-threatening Level 3: Injuries will require hospitalization and can become life-threatening Level 4: Victims are killed by the earthquake
Scenario Capital Stock Losses Income Losses Total Losses (million dollars) (million dollars) (million dollars) New Madrid I 1,097.54 396.37 1,493.90 New Madrid II 6,304.28 1,884.46 8,188.74 New Madrid III 233.74 100.76 334.50 Wabash Valley 1,749.20 654.73 2,403.93 Sharpsburg 2.88 1.0 3.88 KY Seismic & Strong Motion Network
Purposes: 1) monitoring earthquakes (small) 2) monitoring mine blasts 3) strong motion in western KY • Joint project with KGS and EM
• Provide basic information on earthquake hazards and measures that can be taken to mitigate these hazards Example mapping projects: Seismic Soils Map DaviessComposite Co., Seismic Ky. Soils Map, Daviess County, Kentucky ³
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0 2.5 5 10 Miles Summary
• KGS conducts research investigating landslides, karst environments, earthquakes, radon, and other geologic hazards
• Always looking for further collaborating with communities and government agencies on projects that support hazard assessment and efforts to reduce risk
William Andrews Matt Crawford
[email protected] [email protected]
Landslide examples in Kentucky
Ballard Co., Ky. Union Co., Ky. Landslide in loess Hickman Co., Ky. Columbus Belmont Park McCracken Co., Ky.
Old landslide/bank collapse McCracken Co., Ky. Old Ledbetter Bridge McCracken Co., Ky. Old Ledbetter Bridge McCracken Co., Ky. Old Ledbetter Bridge Paducah, Ky. Carroll Co., Ky. 4/2014 Landslide stabilization
Kenton Co., Ky. Maxey Flats, Fleming Co., KY Maxey Flats, Fleming Co., KY Floyd Co., Ky. Perry Co., Ky. 2006 Boyd Co., Ky. Hurricane Camille • Night of August 19-20, 1969 remnants of Hurricane Camille moved from the gulf coast across the Appalachian mountains, stabilized over central Virginia • Within 8 hours, at least 31 in of rain fell producing debris flows and flooding and claiming 150 lives (almost all in Nelson Co.) • Debris flows and floods damaged roads, bridges, communications, houses, farms, and livestock Hyper-concentrated rainfall • Nelson County, VA is characterized by steep slopes and highly dissected topography • Camille triggered ~3,700 landslides, completely devastating about 65mi2 • Almost every 1st order stream channel became a debris flow chute • Several runout distances were documented as exceeding 2 miles
Photo: Dick Whitehead, Oakland Museum Photo: Brower York, Oakland Museum Nelson County, Va. Example: LiDAR derived hillshade DEM with contours
Mapped landslide Mapping Landslides Using LiDAR Lewis County, Ky. Mapping Landslides Using LiDAR Floyd County, Ky.