Publications

California?s 35 million people live among some of the most active earthquake faults in the United States. Public safety demands credible assessments of the earthquake hazard to maintain appropriate building codes for safe construction and earthquake insurance for loss protection. Seismic hazard analysis begins with an earthquake rupture forecast?a model of probabilities that earthquakes...

In a new comprehensive study, scientists have determined that the chance of having one or more magnitude 6.7 or larger earthquakes in the California area over the next 30 years is greater than 99%. Such quakes can be deadly, as shown by the 1989 magnitude 6.9 Loma Prieta and the 1994 magnitude 6.7 Northridge earthquakes. The likelihood of at least one even more powerful quake of...

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...

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...

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...

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...

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...

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...

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...

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...

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...

Rainfall-triggered landslides are part of a natural process of hillslope erosion that can result in catastrophic loss of life and extensive property damage in mountainous, densely populated areas. As global population expansion on or near steep hillslopes continues, the human and economic costs associated with landslides will increase. Landslide hazard mitigation strategies generally...