Research Hydrologist
Volcano Science Center
Email:
shaulh@usgs.gov
Office Phone:
650-439-2441
ORCID:
0000-0001-5142-6886
Supervisor:
Andrew T Calvert
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Quantitative understanding of groundwater and gas-rich fluid- and thermodynamics in volcanic areas is important for several reasons: 1) as a major source of hazard such as propellant in steam-driven explosions, lubricant in mudflows, and transport agent for toxic constituents such as arsenic and mercury that are dissolved from fresh volcanic rock, 2) groundwater pressure, temperature and chemical changes might signal one of the earliest warnings of volcanic unrest, 3) exploration and mining of geothermal energy and mineral deposits. Many of the geochemical, geodetic, and seismic signals measured at the ground surface as part of the volcano monitoring strategies have hydrothermal origins or magmatic origins modulated...
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Note: No formal accuracy tests were conducted and these data are disseminated to allow discussion related to methods. Sample Analyses: Samples were processed at both the USGS in Menlo Park, CA, and at UC Berkeley following established methodology for separating organic material from sinter (Howald et al., 2014; Lowenstern et al., 2016; Slagter et al., 2019). First, the exterior surface of each sample was removed using a rock saw, and then any further material was removed if there was any visible algal material in the interior of the sample. Second, samples underwent a series of chemical baths. Samples were crushed and soaked in 30% hydrogen peroxide for 48 hours to remove any remaining modern algae. Once cleaned,...
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The Yellowstone Plateau Volcanic field consists of lavas from the last two million years. The most recent volcanic units are the Central Plateau Member and the older Upper Basin Member rhyolites (Christiansen, 2001). Investigations into the elemental and isotopic composition of these lavas can provide insight into the recent volcanic history of the different eruptive episodes and provide constraints on the hydrothermal fluid compositions that result from water-rock interactions occurring at depth within the hydrothermal system. In this Data Release, seventeen samples of Yellowstone rhyolite samples from Upper Basin and Central Plateau Member lava flows were analyzed for volatile element compositions via x-ray fluorescence...
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Sample Analyses: Thin sections made at UC Berkeley were brought to the USGS, Menlo Park, CA and were coated with 25 nm carbon. Samples were analyzed at the USGS in Menlo Park, CA in a Tescan VEGA3 Scanning Electron Microscope (SEM) equipped with an Oxford 50 mm2 X-MaxN energy dispersive spectrometer. Thin sections were imaged with backscatter electrons. Energy dispersive X-ray spectroscopy (EDS) analyses and images were collected with an accelerating voltage of 15 kV and a working distance of 15 mm. Database Contents: The data files for “Energy Dispersive X-ray Spectroscopy (EDS) Data” contain representative element spectra analyses of samples UGB-TD-28, -30, -31, -32, -33, -36.
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To characterize eruption activity of the iconic Old Faithful Geyser in Yellowstone National Park over past centuries, we obtained 41 new radiocarbon dates of mineralized wood preserved in the mound of silica that precipitated from erupted waters. Trees do not grow on active geyser mounds, implying that trees grew on the Old Faithful Geyser mound during a protracted period of eruption quiescence. Rooted stumps and root crowns located on higher parts of the mound are evidence that at the time of tree growth, the geyser mound closely resembled its current appearance. The range of calibrated radiocarbon dates (1233–1362 CE) is coincident with a series of severe multidecadal regional droughts toward the end of the Medieval...
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