Publications
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Chlorine degassing during the lava dome-building eruption of Mount St. Helens, 2004-2005
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
Authors
Marie Edmonds, Kenneth A. McGee, Michael P. Doukas
Absolute and relative locations of earthquakes at Mount St. Helens, Washington, using continuous data: Implications for magmatic processes
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
Authors
Weston A. Thelen, Robert S. Crosson, Kenneth C. Creager
Emission rates of CO2, SO2, and H2S, scrubbing, and preeruption excess volatiles at Mount St. Helens, 2004-2005
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
Authors
Terrence M. Gerlach, Kenneth A. McGee, Michael P. Doukas
Near-real-time information products for Mount St. Helens -- tracking the ongoing eruption
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
Authors
Anthony I. Qamar, Stephen Malone, Seth C. Moran, William P. Steele, Weston A. Thelen
Pre- and post-eruptive investigations of gas and water samples from Mount St. Helens, Washington, 2002 to 2005
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
Authors
D. Bergfeld, William C. Evans, Kenneth A. McGee, Kurt R. Spicer
Seismicity associated with renewed dome building at Mount St. Helens, 2004-2005
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
Authors
Seth C. Morgan, Stephen D. Malone, Anthony I. Qamar, Weston A. Thelen, Amy K. Wright, Jacqueline Caplan-Auerbach
Hazard information management during the autumn 2004 reawakening of Mount St. Helens volcano, Washington
The 2004 reawakening of Mount St. Helens quickly
caught the attention of government agencies as well as the
international news media and the public. Immediate concerns
focused on a repeat of the catastrophic landslide and blast
event of May 18, 1980, which remains a vivid memory for
many individuals. Within several days of the onset of accelerating seismicity, media inquiries increased expone
Authors
Carolyn L. Driedger, Christina A. Neal, Tom H. Knappenberger, Deborah H. Needham, Robert B. Harper, William P. Steele
Overview of the 2004 to 2006, and continuing, eruption of Mount St. Helens, Washington
Rapid onset of unrest at Mount St. Helens on September 23, 2004, initiated an uninterrupted lava-dome-building eruption that continues to the time of writing this overview (spring 2006) for a volume of papers focused on this eruption. About three weeks of intense seismic unrest and localized surface uplift, punctuated by four brief explosions, constituted a ventclearing phase, during which there w
Authors
William E. Scott, David R. Sherrod, Cynthia A. Gardner
Managing public and media response to a reawakening volcano: lessons from the 2004 eruptive activity of Mount St. Helens
Volcanic eruptions and other infrequent, large-scale
natural disturbances pose challenges and opportunities for
public-land managers. In the days and weeks preceding an
eruption, there can be considerable uncertainty surrounding
the magnitude and areal extent of eruptive effects. At the same
time, public and media interest in viewing developing events
is high and concern for public safety on
Authors
Peter M. Frenzen, Michael T. Matarrese
Note from the Hubbert Quorum
No abstract available.
Authors
Steven E. Ingebritsen, Shaul Hurwitz, E. E. Brodsky
Variability of passive gas emissions, seismicity, and deformation during crater lake growth at White Island Volcano, New Zealand, 2002-2006
We report on 4 years of airborne measurements of CO2, SO2, and H2S emission rates during a quiescent period at White Island volcano, New Zealand, beginning in 2003. During this time a significant crater lake emerged, allowing scrubbig processes to be investigated. CO2 emissions varied from a baseline of 250 to >2000 t d-1 and demonstrated clear annual cycling that was consistent with numbers of ea
Authors
C. Werner, T. Hurst, B. Scott, S. Sherburn, B.W. Christenson, K. Britten, J. Cole-Baker, B. Mullan
Modeled tephra ages from lake sediments, base of Redoubt Volcano, Alaska
A 5.6-m-long lake sediment core from Bear Lake, Alaska, located 22 km southeast of Redoubt Volcano, contains 67 tephra layers deposited over the last 8750 cal yr, comprising 15% of the total thickness of recovered sediment. Using 12 AMS 14C ages, along with the 137Cs and 210Pb activities of recent sediment, we evaluated different models to determine the age-depth relation of the core, and to deter
Authors
C.J. Schiff, D. S. Kaufman, K.L. Wallace, A. Werner, T.-L. Ku, T. A. Brown