Publications
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Preliminary Geologic Map of Mount Pagan Volcano, Pagan Island, Commonwealth of the Northern Mariana Islands
Pagan Island is the subaerial portion of two adjoining Quaternary stratovolcanoes near the middle of the active Mariana Arc, [FAT1]north of Saipan. Pagan and the other volcanic islands that constitute part of the Arc form the northern half of the East Mariana Ridge[FAT2], which extends about 2-4 km above the ocean floor. The > 6-km-deep Mariana Trench adjoins the East Mariana Ridge on the east, an
Authors
Frank A. Trusdell, Richard B. Moore, Maurice K. Sako
Forecasting runout of rock and debris avalanches
Physically based mathematical models and statistically based empirical equations each may provide useful means of forecasting runout of rock and debris avalanches. This paper compares the foundations, strengths, and limitations of a physically based model and a statistically based forecasting method, both of which were developed to predict runout across three-dimensional topography. The chief adva
Authors
Richard M. Iverson
Volcanic history and 40Ar/39Ar and 14C geochronology of Terceira Island, Azores, Portugal
Seven new 40Ar/39Ar and 23 new radiocarbon ages of eruptive units, in support of new geologic mapping, improve the known chronology of Middle to Late Pleistocene and Holocene volcanic activity on the island of Terceira, Azores and define an east-to-west progression in stratovolcano growth. The argon ages indicate that Cinco Picos Volcano, the oldest on Terceira, completed its main subaerial cone b
Authors
Andrew T. Calvert, Richard B. Moore, John P. McGeehin, Antonio Rodrigues da Silva
Monitoring super-volcanoes: Geophysical and geochemical signals at Yellowstone and other large caldera systems
Earth's largest calderas form as the ground collapses during immense volcanic eruptions, when hundreds to thousands of cubic kilometres of magma are explosively withdrawn from the Earth's crust over a period of days to weeks. Continuing long after such great eruptions, the resulting calderas often exhibit pronounced unrest, with frequent earthquakes, alternating uplift and subsidence of the ground
Authors
Jacob B. Lowenstern, Robert B. Smith, David P. Hill
Geochemistry of low-temperature springs northwest of Yellowstone caldera: Seeking the link between seismicity, deformation, and fluid flow
A comprehensive geochemical survey of springs outside the northwest margin of the Yellowstone caldera was undertaken in 2003 and 2004. This survey was designed to detect: (1) active leakage from a huge reservoir of CO2 gas recently postulated to extend from beneath the caldera into this area; and (2) lingering evidence for subsurface flow of magmatic fluids into this area during the 1985 seismic s
Authors
William C. Evans, Deborah Bergfeld, Matthias C. van Soest, Mark Huebner, John Fitzpatrick, Kinga M. Revesz
Modelling and understanding volcanic processes using high-quality seismological data
At an active volcano,Very-Long-Period (VLP) seismicity(with typical periods in the range 2-100 s) reflects pressure fluctuations resulting from unsteady mass transport in the sub-surface plumbing system,and hence provides a glimpse of the internal dynamics of the volcanic edifice. Understanding the fundamental fluid-flow mechanisms involved in the generation of VLP seismic events is,therefore, key
Authors
Bernard A. Chouet
Atmospheric mercury emissions from substrates and fumaroles associated with three hydrothermal systems in the western United States
This paper quantifies atmospheric mercury (Hg) emissions from substrates and fumaroles associated with three hydrothermal systems: Lassen Volcanic Center, California (LVC); Yellowstone Caldera, Wyoming (YC); and Dixie Valley, Nevada (DV). Substrate Hg fluxes were measured using field chamber methods at thermal and nonthermal sites. The highest Hg fluxes (up to 541 ng m−2 h−1) were measured at ther
Authors
Mark A. Engle, Mae S. Gustin, Fraser Goff, Dale Counce, Cathy J. Janik, Deborah Bergfeld, James J. Rytuba
Peak flow responses to landscape disturbances caused by the cataclysmic 1980 eruption of Mount St. Helens, Washington
Years of discharge measurements that precede and follow the cataclysmic 1980 eruption of Mount St. Helens, Washington, provide an exceptional opportunity to examine the responses of peak flows to abrupt, widespread, devastating landscape disturbance. Multiple basins surrounding Mount St. Helens (300–1300 km2 drainage areas) were variously disturbed by: (1) a debris avalanche that buried 60 km2 of
Authors
Jon J. Major, Linda E. Mark
Perspectives on basaltic magma crystallization and differentiation: Lava-lake blocks erupted at Mauna Loa volcano summit, Hawaii
Explosive eruptions at Mauna Loa summit ejected coarse-grained blocks (free of lava coatings) from Moku'aweoweo caldera. Most are gabbronorites and gabbros that have 0–26 vol.% olivine and 1–29 vol.% oikocrystic orthopyroxene. Some blocks are ferrogabbros and diorites with micrographic matrices, and diorite veins (≤2 cm) cross-cut some gabbronorites and gabbros. One block is an open-textured dunit
Authors
Renee L. McCarter, R.V. Fodor, Frank A. Trusdell
Eruptive history and geochronology of Mount Mazama and the Crater Lake region, Oregon
Geologic mapping, K-Ar, and 40Ar/39Ar age determinations, supplemented by paleomagnetic measurements and geochemical data, are used to quantify the Quaternary volcanic history of the Crater Lake region in order to define processes and conditions that led to voluminous explosive eruptions. The Cascade arc volcano known as Mount Mazama collapsed during its climactic eruption of ∼50 km3 of mainly rhy
Authors
Charles R. Bacon, Marvin A. Lanphere
Sustained long-period seismicity at Shishaldin Volcano, Alaska
From September 1999 through April 2004, Shishaldin Volcano, Aleutian Islands, Alaska, exhibited a continuous and extremely high level of background seismicity. This activity consisted of many hundreds to thousands of long-period (LP; 1–2 Hz) earthquakes per day, recorded by a 6-station monitoring network around Shishaldin. The LP events originate beneath the summit at shallow depths (0–3 km). Volc
Authors
Tanja Petersen, Jacqueline Caplan-Auerbach, Stephen R. McNutt
Real-time monitoring and massive inversion of source parameters of very long period seismic signals: An application to Stromboli Volcano, Italy
We present a comprehensive processing tool for the real‐time analysis of the source mechanism of very long period (VLP) seismic data based on waveform inversions performed in the frequency domain for a point source. A search for the source providing the best‐fitting solution is conducted over a three‐dimensional grid of assumed source locations, in which the Green's functions associated with each
Authors
E. Auger, L. D'Auria, M. Martini, B. Chouet, P. Dawson