Publications
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Late Pleistocene ages for the most recent volcanism and glacial-pluvial deposits at Big Pine volcanic field, California, USA, from cosmogenic 36Cl dating
The Big Pine volcanic field is one of several Quaternary volcanic fields that poses a potential volcanic hazard along the tectonically active Owens Valley of east-central California, and whose lavas are interbedded with deposits from Pleistocene glaciations in the Sierra Nevada Range. Previous geochronology indicates an ∼1.2 Ma history of volcanism, but the eruption ages and distribution of volcan
Authors
Jorge A. Vazquez, Jeff M Woolford
Controls on the breach geometry and flood hydrograph during overtopping of non-cohesive earthen dams
Overtopping failure of non-cohesive earthen dams was investigated in 13 large-scale experiments with dams built of compacted, damp, fine-grained sand. Breaching was initiated by cutting a notch across the dam crest and allowing water escaping from a finite upstream reservoir to form its own channel. The channel developed a stepped profile, and upstream migration of the steps, which coalesced into
Authors
Joseph S. Walder, Richard M. Iverson, Jonathan W. Godt, Matthew Logan, Stephen A. Solovitz
Plugs or flood-makers? the unstable landslide dams of eastern Oregon
Landslides into valley bottoms can affect longitudinal profiles of rivers, thereby influencing landscape evolution through base-level changes. Large landslides can hinder river incision by temporarily damming rivers, but catastrophic failure of landslide dams may generate large floods that could promote incision. Dam stability therefore strongly modulates the effects of landslide dams and might be
Authors
Elizabeth B. Safran, Jim E. O'Connor, Lisa L. Ely, Kyle House, Gordon E. Grant, Kelsey Harrity, Kelsey Croall, Emily Jones
By
Energy and Minerals Mission Area, Natural Hazards Mission Area, Energy Resources Program, Groundwater and Streamflow Information Program, Landslide Hazards Program, Mineral Resources Program, National Laboratories Program, Science and Decisions Center, Volcano Hazards Program, Volcano Science Center, Geologic Hazards Science Center, Geology, Minerals, Energy, and Geophysics Science Center
Source mechanism of small long-period events at Mount St. Helens in July 2005 using template matching, phase-weighted stacking, and full-waveform inversion
Long-period (LP, 0.5-5 Hz) seismicity, observed at volcanoes worldwide, is a recognized signature of unrest and eruption. Cyclic LP “drumbeating” was the characteristic seismicity accompanying the sustained dome-building phase of the 2004–2008 eruption of Mount St. Helens (MSH), WA. However, together with the LP drumbeating was a near-continuous, randomly occurring series of tiny LP seismic events
Authors
Robin S. Matoza, Bernard A. Chouet, Phillip B. Dawson, Peter M. Shearer, Matthew M. Haney, Gregory P. Waite, Seth C. Moran, T. Dylan Mikesell
2013 volcanic activity in Alaska: summary of events and response of the Alaska Volcano Observatory
The Alaska Volcano Observatory (AVO) responded to eruptions, volcanic unrest or suspected unrest, and seismic events at 18 volcanic centers in Alaska during 2013. Beginning with the 2013 AVO Summary of Events, the annual description of the AVO seismograph network and activity, once a stand-alone publication, is now part of this report. Because of this change, the annual summary now contains an exp
Authors
James P. Dixon, Cheryl Cameron, Robert G. McGimsey, Christina A. Neal, Chris Waythomas
Months between rejuvenation and volcanic eruption at Yellowstone caldera, Wyoming
Rejuvenation of previously intruded silicic magma is an important process leading to effusive rhyolite, which is the most common product of volcanism at calderas with protracted histories of eruption and unrest such as Yellowstone, Long Valley, and Valles, USA. Although orders of magnitude smaller in volume than rare caldera-forming super-eruptions, these relatively frequent effusions of rhyolite
Authors
Christy B. Till, Jorge A. Vazquez, Jeremy W Boyce
Origins of geothermal gases at Yellowstone
Gas emissions at the Yellowstone Plateau Volcanic Field (YPVF) reflect open-system mixing of gas species originating from diverse rock types, magmas, and crustal fluids, all combined in varying proportions at different thermal areas. Gases are not necessarily in chemical equilibrium with the waters through which they vent, especially in acid sulfate terrain where bubbles stream through stagnant ac
Authors
Jacob B. Lowenstern, Deborah Bergfeld, William C. Evans, Andrew G. Hunt
Eruptive and environmental processes recorded by diatoms in volcanically-dispersed lake sediments from the Taupo Volcanic Zone, New Zealand
Late Pleistocene diatomaceous sediment was widely dispersed along with volcanic ash (tephra) across and beyond New Zealand by the 25.4 ka Oruanui supereruption from Taupo volcano. We present a detailed analysis of the diatom populations in the Oruanui tephra and the newly discovered floras in two other eruptions from the same volcano: the 28.6 ka Okaia and 1.8 ka Taupo eruptions. For comparison, t
Authors
Margaret A. Harper, Shirley A. Pledger, Euan G. C. Smith, Alexa R. Van Eaton, Colin J. N. Wilson
Age of the Lava Creek supereruption and magma chamber assembly at Yellowstone based on 40Ar/39Ar and U-Pb dating of sanidine and zircon crystals
The last supereruption from the Yellowstone Plateau formed Yellowstone caldera and ejected the >1000 km3 of rhyolite that composes the Lava Creek Tuff. Tephra from the Lava Creek eruption is a key Quaternary chronostratigraphic marker, in particular for dating the deposition of mid Pleistocene glacial and pluvial deposits in western North America. To resolve the timing of eruption and crystallizat
Authors
Naomi E. Matthews, Jorge A. Vazquez, Andrew T. Calvert
Digital database of channel cross-section surveys, Mount St. Helens, Washington
Stream-channel cross-section survey data are a fundamental component to studies of fluvial geomorphology. Such data provide important parameters required by many open-channel flow models, sediment-transport equations, sediment-budget computations, and flood-hazard assessments. At Mount St. Helens, Washington, the long-term response of channels to the May 18, 1980, eruption, which dramatically alte
Authors
Adam R. Mosbrucker, Kurt R. Spicer, Jon J. Major, Dennis R. Saunders, Tami S. Christianson, Cole G. Kingsbury
Hail formation triggers rapid ash aggregation in volcanic plumes
During explosive eruptions, airborne particles collide and stick together, accelerating the fallout of volcanic ash and climate-forcing aerosols. This aggregation process remains a major source of uncertainty both in ash dispersal forecasting and interpretation of eruptions from the geological record. Here we illuminate the mechanisms and timescales of particle aggregation from a well-characterize
Authors
Alexa R. Van Eaton, Larry G. Mastin, M. Herzog, Hans F. Schwaiger, David J. Schneider, Kristi L. Wallace, Amanda B Clarke
Measurement of slow-moving along-track displacement from an efficient multiple-aperture SAR interferometry (MAI) stacking
Multiple-aperture SAR interferometry (MAI) has demonstrated outstanding measurement accuracy of along-track displacement when compared to pixel-offset-tracking methods; however, measuring slow-moving (cm/year) surface displacement remains a challenge. Stacking of multi-temporal observations is a potential approach to reducing noise and increasing measurement accuracy, but it is difficult to achiev
Authors
Min-Jeong Jo, Hyung-Sup Jung, Joong-Sun Won, Michael P. Poland, Asta Miklius, Zhong Lu