Publications
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Initiation conditions for debris flows generated by runoff at Chalk Cliffs, central Colorado
We have monitored initiation conditions for six debris flows between May 2004 and July 2006 in a 0.3 km2 drainage basin at Chalk Cliffs; a band of hydrothermally-altered quartz monzonite in central Colorado. Debris flows were initiated by water runoff from colluvium and bedrock that entrained sediment from rills and channels with slopes ranging from about 14° to 45°. The availability of channel ma
Authors
Jeffrey A. Coe, David Kinner, Jonathan W. Godt
Monitoring the Earth's dynamic magnetic field
The mission of the U.S. Geological Survey's Geomagnetism Program is to monitor the Earth's magnetic field. Using ground-based observatories, the Program provides continuous records of magnetic field variations covering long timescales; disseminates magnetic data to various governmental, academic, and private institutions; and conducts research into the nature of geomagnetic variations for purposes
Authors
Jeffrey J. Love, David Applegate, John B. Townshend
Maximum spectral demands in the near-fault region
The Next Generation Attenuation (NGA) relationships for shallow crustal earthquakes in the western United States predict a rotated geometric mean of horizontal spectral demand, termed GMRotI50, and not maximum spectral demand. Differences between strike-normal, strike-parallel, geometric-mean, and maximum spectral demands in the near-fault region are investigated using 147 pairs of records selecte
Authors
Yin-Nan Huang, Andrew S. Whittaker, Nicolas Luco
Post-Wildfire Hydrologic Hazards in the Wildland Urban Interface of Colorado and the Western United States
Following a wildfire, such as the 2002 Missionary Ridge fire, a number of hydrologic hazards may develop that can have an important impact on water resources, businesses, homes, reservoirs, roads, and utilities in the wildland urban interface (areas where homes and commercial developments are interspersed with wildlands) in mountainous areas of the Western United States. This fact sheet describes
Authors
M. R. Stevens, C. R. Bossong, M.G. Rupert, A.J. Ranalli, E.W. Cassidy, A.D. Druliner
Lightning‐driven electric fields measured in the lower ionosphere: Implications for transient luminous events
Transient luminous events above thunderstorms such as sprites, halos, and elves require large electric fields in the lower ionosphere. Yet very few in situ measurements in this region have been successfully accomplished, since it is typically too low in altitude for rockets and satellites and too high for balloons. In this article, we present some rare examples of lightning‐driven electric field c
Authors
Jeremy N. Thomas, Benjamin H. Barnum, Erin Lay, Robert H. Holzworth, Mengu Cho, Michael C. Kelley
Paleoseismicity and neotectonics of the Aleutian subduction zone — An overview
The Aleutian subduction zone is one of the most seismically active plate boundaries and the source of several of the world’s largest historic earthquakes. The structural architecture of the subduction zone varies considerably along its length. At the eastern end is a tectonically complex collision zone where the allochthonous Yakutat terrane is moving northwest into mainland Alaska. West of the co
Authors
Gary A. Carver, George Plafker
Toward a time-dependent probabilistic seismic hazard analysis for Alaska
We report on a time-dependent seismic hazard analysis for Alaska and the Aleutians to complement our recently completed time-independent map. Whereas the time-independent map treats all sources as statistically independent, the time-dependent analysis is based on calculations of the conditional probability of occurrence for the next 50 years by using a Brownian Passage Time model for the seismic s
Authors
Oliver S. Boyd, Yuehua Zeng, Charles G. Bufe, Robert L. Wesson, Fred Pollitz, Jeanne L. Hardebeck
Does a boundary of the Wrangell Block extend through southern Cook Inlet and Shelikof Strait, Alaska?
In southcentral Alaska, the boundaries of two different tectonic blocks extend southwestward from the Denali Fault toward Cook Inlet and Shelikof Strait. We use offshore multichannel seismic reflection data and oil-well stratigraphy to evaluate whether local geologic structures are compatible with boundaries of either tectonic block and with the relative motion expected across the block boundaries
Authors
Michael A. Fisher, Ray W. Sliter, Florence L. Wong
Numerical modeling of rainfall thresholds for shallow landsliding in the Seattle, Washington, area
The temporal forecasting of landslide hazard has typically relied on empirical relations between rainfall characteristics and landslide occurrence to identify conditions that may cause shallow landslides. Here, we describe an alternate, deterministic approach to define rainfall thresholds for landslide occurrence in the Seattle, Washington, area. This approach combines an infinite slope-stability
Authors
Jonathan W. Godt, Jonathan P. McKenna
The role of shear and tensile failure in dynamically triggered landslides
Dynamic stresses generated by earthquakes can trigger landslides. Current methods of landslide analysis such as pseudo-static analysis and Newmark's method focus on the effects of earthquake accelerations on the landslide mass to characterize dynamic landslide behaviour. One limitation of these methods is their use Mohr-Coulomb failure criteria, which only accounts for shear failure, but the role
Authors
T.L. Gipprich, R.K. Snieder, R. W. Jibson, W. Kimman
A comparative analysis of simulated and observed landslide locations triggered by Hurricane Camille in Nelson County, Virginia
In 1969, Nelson County, Virginia received up to 71 cm of rain within 12 h starting at 7 p.m. on August 19. The total rainfall from the storm exceeded the 1000-year return period in the region. Several thousands of landslides were induced by rainfall associated with Hurricane Camille causing fatalities and destroying infrastructure. We apply a distributed transient response model for regional slope
Authors
M.M. Morrissey, G. F. Wieczorek, B. A. Morgan
Modeling the spatial distribution of landslide-prone colluvium and shallow groundwater on hillslopes of Seattle, WA
Landslides in partially saturated colluvium on Seattle, WA, hillslopes have resulted in property damage and human casualties. We developed statistical models of colluvium and shallow-groundwater distributions to aid landslide hazard assessments. The models were developed using a geographic information system, digital geologic maps, digital topography, subsurface exploration results, the groundwate
Authors
W.H. Schulz, D. J. Lidke, J. W. Godt