Publications

Explosive eruptions at basaltic volcanoes have been linked to gas segregation from magmas at shallow depths in the crust. The composition of primary melts formed at greater depths was thought to have little influence on eruptive style. Ocean island basaltic volcanoes are the product of melting of a geochemically heterogeneous mantle plume and are expected to give rise to heterogeneous...

Newberry Volcano in central Oregon is a 3,100-square-kilometer (1,200-square-mile) shield-shaped composite volcano, occupying a location east of the main north-south trend of the High Cascades volcanoes and forming a transition between the High Lava Plains subprovince of the Basin and Range Province to the east and the Cascade Range to the west. Magnetic, gravity, and radiometric data...

The Alaska Volcano Observatory (AVO) responded to eruptions, possible eruptions, volcanic unrest, and reports of unusual activity at or near eight separate volcanic centers in Alaska during 2009. The year was highlighted by the eruption of Redoubt Volcano, one of three active volcanoes on the western side of Cook Inlet and near south-central Alaska's population and commerce centers...

A panel of leading experts (The Old Faithful Science Review Panel) was convened by Yellowstone National Park (YNP) to review and summarize the geological and hydrological understanding that can inform National Park Service management of the Upper Geyser Basin area. We give an overview of present geological and hydrological knowledge of the Old Faithful hydrothermal (hot water) system and...

During volcanic eruptions, empirical relationships are used to estimate mass eruption rate from plume height. Although simple, such relationships can be inaccurate and can underestimate rates in windy conditions. One-dimensional plume models can incorporate atmospheric conditions and give potentially more accurate estimates. Here I present a 1-D model for plumes in crosswind and simulate...

Laharz_py is written in the Python programming language as a suite of tools for use in ArcMap Geographic Information System (GIS). Primarily, Laharz_py is a computational model that uses statistical descriptions of areas inundated by past mass-flow events to forecast areas likely to be inundated by hypothetical future events. The forecasts use physically motivated and statistically...

We analyze intervals between eruptions (IBEs) data acquired between 2001 and 2011 at Daisy and Old Faithful geysers in Yellowstone National Park. We focus our statistical analysis on the response of these geysers to stress perturbations from within the solid earth (earthquakes and earth tides) and from weather (air pressure and temperature, precipitation, and wind). We conclude that (1)...

Backprojection has become a powerful tool for imaging the rupture process of global earthquakes. We demonstrate the ability of backprojection to illuminate and track volcanic sources as well. We apply the method to the seismic network from Okmok Volcano, Alaska, at the time of an escalation in tremor during the 2008 eruption. Although we are able to focus the wavefield close to the...

From August 26 to September 5, 2011, the U.S. Geological Survey (USGS) collected more than 600 line-kilometers of shipborne magnetic data on Mono Lake, 20 line-kilometers of ground magnetic data on Paoha Island, 50 gravity stations on Paoha and Negit Islands, and 28 rock samples on Paoha and Negit Islands, in east-central California. Magnetic and gravity investigations were undertaken in...

Unrest at Mammoth Mountain over the past several decades, manifest by seismicity, ground deformation, diffuse CO2 emissions, and elevated 3He/4He ratios in fumarolic gases has been driven by the release of CO2-rich fluids from basaltic intrusions in the middle to lower crust. Recent unrest included the occurrence of three lower-crustal (32–19 km depth) seismic swarms beneath Mammoth...

Volcanic plumes can be hazardous to aircraft. A correlation between plume height and ground deformation during an eruption of Grímsvötn Volcano, Iceland, allows us to peer into the properties of the magma chamber and may improve eruption forecasts.

Melt inclusions are small droplets of silicate melt that are trapped in minerals during their growth in a magma. Once formed, they commonly retain much of their initial composition (with some exceptions) unless they are re-opened at some later stage. Melt inclusions thus offer several key advantages over whole rock samples: (i) they record pristine concentrations of volatiles and metals...