Publications

Self-contained, single-frequency GPS instruments fitted on lightweight stations suitable for helicopter-sling payloads became a critical part of volcano monitoring during the September 2004 unrest and subsequent eruption of Mount St. Helens. Known as “spiders” because of their spindly frames, the stations were slung into the crater 29 times from September 2004 to December 2005 when conditions

Detecting far-field deformation at Mount St. Helens since the crater-forming landslide and blast in 1980 has been difficult despite frequent volcanic activity and improved monitoring techniques. Between 1982 and 1991, the systematic extension of line lengths in a regional GPS trilateration network is consistent with recharge of a deep magma chamber during that interval. The rate of extension,

We report the results of recent geologic mapping and radiometric dating that add considerable detail to our understanding of the eruptive history of Mount St. Helens before its latest, or Spirit Lake, stage. New data and reevaluation of earlier work indicate at least two eruptive periods during the earliest, or Ape Canyon, stage, possibly separated by a long hiatus: one about 300-250 ka and a seco

This highly specialized book is interesting not only because of its important subject matter but also because of its egocentric perspective. The majority of the book provides a nearly exhaustive retrospective of the authors’ many contributions to the shallow‐flow theory of granular avalanches, and it also critiques contributions by others. Indeed, some readers (including this reviewer) might be di

No abstract available.

From October 2004 to May 2005, the Center for Earthquake Research and Information of the University of Memphis operated two to six broadband seismometers within 5 to 20 km of Mount St. Helens to help monitor recent seismic and volcanic activity. Approximately 57,000 earthquakes identified during the 7-month deployment had a normal magnitude distribution with a mean magnitude of 1.78 and a stan

Remote measurements of volcanic gases from the Mount St. Helens lava dome were carried out using OpenPath Fourier-Transform Infrared spectroscopy on August 31, 2005. Measurements were performed at a site ~1 km from the lava dome, which was used as a source of IR radiation. On average, during the period of measurement, the volcanic gas contained 99 mol percent H2 O, 0.78 percent CO2 , 0.095 p

This study uses a combination of absolute and relative locations from earthquake multiplets to investigate the seismicity associated with the eruptive sequence at Mount St. Helens between September 23, 2004, and November 20, 2004. Multiplets, a prominent feature of seismicity during this time period, occurred as volcano-tectonic, hybrid, and low-frequency earthquakes spanning a large range of

Airborne surveillance of gas emissions began at Mount St. Helens on September 27, 2004. Reconnaissance measurements--SO2 column abundances and CO2 , SO2 , and H2 S concentrations--showed neither a gas plume downwind of the volcano nor gas sources within the crater. Subsequent measurements taken during the period of unrest before the eruption began on October 1 and for several days after Octo

The rapid onset of energetic seismicity on September 23, 2004, at Mount St. Helens caused seismologists at the Pacific Northwest Seismic Network and the Cascades Volcano Observatory to quickly improve and develop techniques that summarized and displayed seismic parameters for use by scientists and the general public. Such techniques included webicorders (Web-based helicorder-like displays), g

Samples of gas and water from thermal springs in Loowit and Step canyons and creeks that drain the crater at Mount St. Helens have been collected since October 2004 to monitor the flux of dissolved magmatic volatiles in the hydrologic system. The changing composition of the waters highlights a trend that began as early as 1994 and includes decreasing SO4 and Cl concentrations and large incr

The reawakening of Mount St. Helens after 17 years and 11 months of slumber was heralded by a swarm of shallow (depth 2 earthquakes were occurring at a rate of ~1 per minute. A gradual transition from volcano-tectonic to hybrid and low-frequency events occurred along with this intensification, a characteristic of many precursory swarms at Mount St. Helens before dome-building eruptions in the