Publications
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Halogen degassing during ascent and eruption of water-poor basaltic magma
A study of volcanic gas composition and matrix glass volatile concentrations has allowed a model for halogen degassing to be formulated for K??lauea Volcano, Hawai'i. Volcanic gases emitted during 2004-2005 were characterised by a molar SO2/HCl of 10-64, with a mean of 33; and a molar HF/HCl of 0-5, with a mean of 1.0 (from approximately 2500 measurements). The HF/HCl ratio was more variable than
Authors
M. Edmonds, T.M. Gerlach, Richard A. Herd
Numerical models of caldera deformation: Effects of multiphase and multicomponent hydrothermal fluid flow
Ground surface displacement (GSD) in large calderas is often interpreted as resulting from magma intrusion at depth. Recent advances in geodetic measurements of GSD, notably interferometric synthetic aperture radar, reveal complex and multifaceted deformation patterns that often require complex source models to explain the observed GSD. Although hydrothermal fluids have been discussed as a possibl
Authors
M. Hutnak, S. Hurwitz, S. E. Ingebritsen, P. A. Hsieh
SBAS-InSAR analysis of surface deformation at Mauna Loa and Kilauea volcanoes in Hawaii
We investigate the deformation of Mauna Loa and Kllauea volcanoes, Hawai'i, by exploiting the advanced differential Synthetic Aperture Radar Interferometry (InSAR) technique referred to as the Small BAseline Subset (SBAS) algorithm. In particular, we present time series of line-of-sight (LOS) displacements derived from SAR data acquired by the ASAR instrument, on board the ENVISAT satellite, from
Authors
F. Casu, Riccardo Lanari, E. Sansosti, G. Solaro, Pietro Tizzani, M. Poland, Asta Miklius
Volcanism and associated hazards: The Andean perspective
Andean volcanism occurs within the Andean Volcanic Arc (AVA), which is the product of subduction of the Nazca Plate and Antarctica Plates beneath the South America Plate. The AVA is Earth's longest but discontinuous continental-margin volcanic arc, which consists of four distinct segments: Northern Volcanic Zone, Central Volcanic Zone, Southern Volcanic Zone, and Austral Volcanic Zone. These segme
Authors
R. I. Tilling
Non-double-couple mechanisms of microearthquakes induced by hydraulic fracturing
We have inverted polarity and amplitude information of representative microearthquakes to investigate source mechanisms of seismicity induced by hydraulic fracturing in the Carthage Cotton Valley, east Texas, gas field. With vertical arrays of four and eight three-component geophones in two monitoring wells, respectively, we were able to reliably determine source mechanisms of the strongest events
Authors
J. Sileny, D. P. Hill, Leo Eisner, F.H. Cornet
Isotopic and trace element constraints on the petrogenesis of lavas from the Mount Adams volcanic field, Washington
Strontium, Nd, Pb, Hf, Os, and O isotope compositions for 30 Quaternary lava flows from the Mount Adams stratovolcano and its basaltic periphery in the Cascade arc, southern Washington, USA indicate a major component from intraplate mantle sources, a relatively small subduction component, and interaction with young mafic crust at depth. Major- and trace-element patterns for Mount Adams lavas are d
Authors
B.R. Jicha, G.L. Hart, C.M. Johnson, Wes Hildreth, B.L. Beard, S.B. Shirey, J.W. Valley
The unexpected awakening of Chaitén Volcano, Chile
On 2 May 2008, a large eruption began unexpectedly at the inconspicuous Chaitén volcano in Chile's southern volcanic zone. Ash columns abruptly jetted from the volcano into the stratosphere, followed by lava dome effusion and continuous low-altitude ash plumes [Lara, 2009]. Apocalyptic photographs of eruption plumes suffused with lightning were circulated globally.
Effects of the eruption were
Authors
Simon A. Carn, John S. Zogorski, Luis Lara, John W. Ewert, Sebastian Watt, Alfred J. Prata, Ronald J. Thomas, Gustavo Villarosa
Hydrometeor-enhanced tephra sedimentation: Constraints from the 18 May 1980 eruption of Mount St. Helens
Uncertainty remains on the origin of distal mass deposition maxima observed in many recent tephra fall deposits. In this study the link between ash aggregation and the formation of distal mass deposition maxima is investigated through reanalysis of tephra fallout from the Mount St. Helens 18 May 1980 (MSH80) eruption. In addition, we collate all the data needed to model distal ash sedimentation fr
Authors
A.J. Durant, William I. Rose, A.M. Sarna-Wojcicki, Steven Carey, A.C.M. Volentik
The source of infrasound associated with long-period events at mount St. Helens
During the early stages of the 2004-2008 Mount St. Helens eruption, the source process that produced a sustained sequence of repetitive long-period (LP) seismic events also produced impulsive broadband infrasonic signals in the atmosphere. To assess whether the signals could be generated simply by seismic-acoustic coupling from the shallow LP events, we perform finite difference simulation of the
Authors
R.S. Matoza, M.A. Garces, B. A. Chouet, L. D'Auria, M.A.H. Hedlin, C. De Groot-Hedlin, G.P. Waite
Discriminating assimilants and decoupling deep- vs. shallow-level crystal records at Mount Adams using 238U-230Th disequilibria and Os isotopes
A suite of 23 basaltic to dacitic lavas erupted over the last 350 kyr from the Mount Adams volcanic field has been analyzed for U–Th isotope compositions to evaluate the roles of mantle versus crustal components during magma genesis. All of the lavas have (230Th/238U) > 1 and span a large range in (230Th/232Th) ratios, and most basalts have higher (230Th/232Th) ratios than andesites and dacites. S
Authors
Brian R. Jicha, Clark M. Johnson, Wes Hildreth, Brian L. Beard, Garret L. Hart, Steven B. Shirey, Brad S. Singer
Interactive effects of fire, soil climate, and moss on CO2 fluxes in black spruce ecosystems of interior Alaska
Fire is an important control on the carbon (C) balance of the boreal forest region. Here, we present findings from two complementary studies that examine how fire modifies soil organic matter properties, and how these modifications influence rates of decomposition and C exchange in black spruce (Picea mariana) ecosystems of interior Alaska. First, we used laboratory incubations to explore soil tem
Authors
Jonathan A. O'Donnell, Merritt R. Turetsky, Jennifer W. Harden, Kristen L. Manies, L.E. Pruett, Gordon Shetler, Jason C. Neff
The United States national volcanic ash operations plan for aviation
Volcanic-ash clouds are a known hazard to aviation, requiring that aircraft be warned away from ash-contaminated airspace. The exposure of aviation to potential hazards from volcanoes in the United States is significant. In support of existing interagency operations to detect and track volcanic-ash clouds, the United States has prepared a National Volcanic Ash Operations Plan for Aviation to stren
Authors
Steven Albersheim, Marianne Guffanti