Publications

Earthquake prediction is a long-sought goal. Changes in groundwater chemistry before earthquakes in Iceland highlight a potential hydrogeochemical precursor, but such signals must be evaluated in the context of long-term, multiparametric data sets.

Maps that define the current distribution of geothermally heated ground are useful toward setting a baseline for thermal activity to better detect and understand future anomalous hydrothermal and (or) volcanic activity. Monitoring changes in the dynamic thermal areas also supports decisions regarding the development of Yellowstone National Park infrastructure, preservation and protection of park r

Strong earthquake ground motion records are fundamental in engineering applications. Ground motion time series are used in response-history dynamic analysis of structural or geotechnical systems. In such analysis, the validity of predicted responses depends on the validity of the input excitations. Ground motion records are also used to develop ground motion prediction equations(GMPEs) for intensi

The frequency-dependent effects of rupture propagation of the Parkfield, California earthquake (Sept. 28, 2004, M6) to the northwest along the San Andreas fault can be seen in acceleration records at UPSAR (USGS Parkfield Seismic Array) in at least two ways. First, we can see the effects of directivity in the acceleration traces at UPSAR, which is about 11.5 km from the epicenter. Directivity or t

Rock falls are common in Yosemite Valley, California, posing substantial hazard and risk to the approximately four million annual visitors to Yosemite National Park. Rock falls in Yosemite Valley over the past few decades have damaged structures and caused injuries within developed regions located on or adjacent to talus slopes highlighting the need for additional investigations into rock-fall haz

Hurricane Sandy caused unprecedented damage across some of the most densely populated coastal areas of the northeastern United States. The costly, landscape-altering destruction left in the wake of this storm is a stark reminder of our Nation’s need to become more resilient as we inevitably face future coastal hazards. As our Nation recovers from this devastating natural disaster, it is clear tha

Using seismic surface waves recorded with Earthscope's Transportable Array, we apply surface wave imaging to determine 3D seismic velocity in the crust and uppermost mantle. Our images span several Proterozoic and early Cambrian rift zones (Mid-Continent Rift, Rough Creek Graben—Rome trough, Birmingham trough, Southern Oklahoma Aulacogen, and Reelfoot Rift). While ancient rifts are generally assoc

The 2013 eruption of Pavlof Volcano, Alaska began on 13 May and ended 49 days later on 1 July. The eruption was characterized by persistent lava fountaining from a vent just north of the summit, intermittent strombolian explosions, and ash, gas, and aerosol plumes that reached as high as 8 km above sea level and on several occasions extended as much as 500 km downwind of the volcano. During the fi

Episode 57 of Kīlauea’s long-lived east rift zone eruption was characterized by lava effusion and spattering within the crater at Puʻu ʻŌʻō that lasted from July 1 to July 20, 2007. This eruptive episode represented a resumption of activity following a 12-day eruptive hiatus on Kīlauea associated with the episode 56 intrusion and eruption near Kāne Nui o Hamo cone, uprift from Puʻu ʻŌʻō, on June 1

The 1989 Loma Prieta earthquake interrupted several decades of seismic tranquility in the San Francisco Bay Area. It caused damage throughout the region and was a wakeup call to prepare for potentially even more damaging future quakes. Since 1989, the work of the U.S. Geological Survey and many other organizations has improved the understanding of the seismic threat in the Bay Area, promoted aware

We cannot yet predict large earthquakes in the short term with much reliability and skill, but the strong clustering exhibited in seismic sequences tells us that earthquake probabilities are not constant in time; they generally rise and fall over periods of days to years in correlation with nearby seismic activity. Operational earthquake forecasting (OEF) is the dissemination of authoritative info

This paper extends Culmann's vertical-cut analysis to unsaturated soils. To test the extended theory, unsaturated sand was compacted to a uniform porosity and moisture content in a laboratory apparatus. A sliding door that extended the height of the free face of the slope was lowered until the vertical cut failed. Digital images of the slope cross section and upper surface were acquired concurrent