Publications
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Seasonal seismicity at western United States volcanic centers Seasonal seismicity at western United States volcanic centers
We examine 20-yr data sets of seismic activity from 10 volcanic areas in the western United States for annual periodic signals (seasonality), focusing on large calderas (Long Valley caldera and Yellowstone) and stratovolcanoes (Cascade Range). We apply several statistical methods to test for seasonality in the seismic catalogs. In 4 of the 10 regions, statistically significant seasonal...
Authors
L.B. Christiansen, S. Hurwitz, M.O. Saar, S. E. Ingebritsen, P. A. Hsieh
Thermal regulation of methane hydrate dissociation: Implications for gas production models Thermal regulation of methane hydrate dissociation: Implications for gas production models
Thermal self-regulation of methane hydrate dissociation at pressure, temperature conditions along phase boundaries, illustrated by experiment in this report, is a significant effect with potential relevance to gas production from gas hydrate. In surroundings maintained at temperatures above the ice melting point, the temperature in the vicinity of dissociating methane hydrate will...
Authors
S. Circone, Stephen H. Kirby, Laura A. Stern
Catastrophic precipitation-triggered lahar at Casita volcano, Nicaragua: Occurrence, bulking and transformation Catastrophic precipitation-triggered lahar at Casita volcano, Nicaragua: Occurrence, bulking and transformation
A catastrophic lahar began on 30 October 1998, as hurricane precipitation triggered a small flank collapse of Casita volcano, a complex and probably dormant stratovolcano. The initial rockslide‐debris avalanche evolved on the flank to yield a watery debris flood with a sediment concentration less than 60 per cent by volume at the base of the volcano. Within 2·5 km, however, the watery flow...
Authors
K. M. Scott, J.W. Vallance, N. Kerle, J.L. Macias, W. Strauch, G. Devoli
Late Pleistocene granodiorite source for recycled zircon and phenocrysts in rhyodacite lava at Crater Lake, Oregon Late Pleistocene granodiorite source for recycled zircon and phenocrysts in rhyodacite lava at Crater Lake, Oregon
Rhyodacite tephra and three lavas erupted ∼27 ka, interpreted to be early leaks from the climactic magma chamber of Mount Mazama, contain ubiquitous resorbed crystals (antecrysts) that were recycled from young granodiorite and related plutonic rocks of the same magmatic system. The shallow composite pluton is represented by blocks ejected in the 7.7-ka climactic eruption that formed...
Authors
C. R. Bacon, J. B. Lowenstern
Surface deformation associated with the March 1996 earthquake swarm at Akutan Island, Alaska, revealed by C-band ERS and L-band JERS radar interferometry Surface deformation associated with the March 1996 earthquake swarm at Akutan Island, Alaska, revealed by C-band ERS and L-band JERS radar interferometry
In March 1996, an intense earthquake swarm beneath Akutan Island, Alaska, was accompanied by extensive ground cracking but no eruption of Akutan volcano. Radar interferograms produced from L-band JERS-1 and C-band ERS-1/2 images show uplift associated with the swarm by as much as 60 cm on the western part of the island. The JERS-1 interferogram has greater coherence, especially in areas...
Authors
Z. Lu, C. Wicks, O. Kwoun, J.A. Power, D. Dzurisin
An alternative approach to characterize nonlinear site effects An alternative approach to characterize nonlinear site effects
This paper examines the rationale of a method of nonstationary processing and analysis, referred to as the Hilbert-Huang transform (HHT), for its application to a recording-based approach in quantifying influences of soil nonlinearity in site response. In particular, this paper first summarizes symptoms of soil nonlinearity shown in earthquake recordings, reviews the Fourier-based...
Authors
R.R. Zhang, S. Hartzell, J. Liang, Y. Hu
Monitoring eruptive activity at Mount St. Helens with TIR image data Monitoring eruptive activity at Mount St. Helens with TIR image data
Thermal infrared (TIR) data from the MASTER airborne imaging spectrometer were acquired over Mount St. Helens in Sept and Oct, 2004, before and after the onset of recent eruptive activity. Pre‐eruption data showed no measurable increase in surface temperatures before the first phreatic eruption on Oct 1. MASTER data acquired during the initial eruptive episode on Oct 14 showed maximum...
Authors
R.G. Vaughan, S.J. Hook, M.S. Ramsey, V.J. Realmuto, D.J. Schneider
Water alteration of rocks and soils on Mars at the Spirit rover site in Gusev crater Water alteration of rocks and soils on Mars at the Spirit rover site in Gusev crater
Gusev crater was selected as the landing site for the Spirit rover because of the possibility that it once held a lake. Thus one of the rover's tasks was to search for evidence of lake sediments. However, the plains at the landing site were found to be covered by a regolith composed of olivine-rich basaltic rock and wind-blown 'global' dust. The analyses of three rock interiors exposed...
Authors
L.A. Haskin, A. Wang, B.L. Jolliff, H.Y. McSween, B. C. Clark, D.J. Des Marais, S. M. McLennan, N.J. Tosca, J.A. Hurowitz, J.D. Farmer, A. Yen, S. W. Squyres, R. E. Arvidson, G. Klingelhofer, C. Schroder, P.A. De Souza, D. W. Ming, Ralf Gellert, J. Zipfel, J. Bruckner, J.F. Bell, Kenneth E. Herkenhoff, P. R. Christensen, S. Ruff, D. Blaney, S. Gorevan, N.A. Cabrol, L. Crumpler, J. Grant, L. Soderblom
InSAR studies of Alaska volcanoes InSAR studies of Alaska volcanoes
Interferometric synthetic aperture radar (InSAR) is a remote sensing technique capable of measuring ground surface deformation with sub-centimeter precision and spatial resolution in tens-ofmeters over a large region. This paper describes basics of InSAR and highlights our studies of Alaskan volcanoes with InSAR images acquired from European ERS-l and ERS-2, Canadian Radarsat-l, and...
Authors
Zhong Lu, Chuck Wicks, Daniel Dzurisin, John A. Power
Global Positioning System measurements on the island of Hawai`i: 1997 through 2004 Global Positioning System measurements on the island of Hawai`i: 1997 through 2004
This report summarizes GPS data and observations collected between 1997 and 2004 on the island of Hawai‘i with static surveying and continuously recording instruments. On Kīlauea, the long-term deformation field is dominated by steady southeastern velocities of more than 6 cm/year and uplift of about 2 cm/yr at stations on the south flank (with respect to a fixed Pacific Plate)...
Authors
Asta Miklius, Peter Cervelli, Maurice Sako, Michael Lisowski, Susan Owen, Paul Segal, James Foster, Kevan Kamibayashi, Ben Brooks
Gravity and magnetic data along a seismic refraction-reflection line in northwest Nevada and northeast California Gravity and magnetic data along a seismic refraction-reflection line in northwest Nevada and northeast California
No abstract available.
Authors
Janet E. Tilden, David A. Ponce, Jonathan M. G. Glen, Kathleen D. Gans
Argon geochronology of late Pleistocene to Holocene Westdahl volcano, Unimak Island, Alaska Argon geochronology of late Pleistocene to Holocene Westdahl volcano, Unimak Island, Alaska
High-precision 40Ar/39Ar geochronology of selected lavas from Westdahl Volcano places time constraints on several key prehistoric eruptive phases of this large active volcano. A dike cutting old pyroclastic-flow and associated lahar deposits from a precursor volcano yields an age of 1,654+/-11 k.y., dating this precursor volcano as older than early Pleistocene. A total of 11...
Authors
Andrew T. Calvert, Richard B. Moore, Robert G. McGimsey