Rudolph Maxwell L.

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Maxwell L.

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  • Article
    Eruptions at Lone Star Geyser, Yellowstone National Park, USA: 1. Energetics and eruption dynamics
    (John Wiley & Sons, 2013-08-13) Karlstrom, Leif ; Hurwitz, Shaul ; Sohn, Robert A. ; Vandemeulebrouck, Jean ; Murphy, Fred ; Rudolph, Maxwell L. ; Johnston, Malcolm J. S. ; Manga, Michael ; McCleskey, R. Blaine
    Geysers provide a natural laboratory to study multiphase eruptive processes. We present results from a 4 day experiment at Lone Star Geyser in Yellowstone National Park, USA. We simultaneously measured water discharge, acoustic emissions, infrared intensity, and visible and infrared video to quantify the energetics and dynamics of eruptions, occurring approximately every 3 h. We define four phases in the eruption cycle (1) a 28±3 min phase with liquid and steam fountaining, with maximum jet velocities of 16–28 m s−1, steam mass fraction of less than ∼0.01. Intermittently choked flow and flow oscillations with periods increasing from 20 to 40 s are coincident with a decrease in jet velocity and an increase of steam fraction; (2) a 26±8 min posteruption relaxation phase with no discharge from the vent, infrared (IR), and acoustic power oscillations gliding between 30 and 40 s; (3) a 59±13 min recharge period during which the geyser is quiescent and progressively refills, and (4) a 69±14 min preplay period characterized by a series of 5–10 min long pulses of steam, small volumes of liquid water discharge, and 50–70 s flow oscillations. The erupted waters ascend from a 160–170°C reservoir, and the volume discharged during the entire eruptive cycle is 20.8±4.1 m3. Assuming isentropic expansion, we calculate a heat output from the geyser of 1.4–1.5 MW, which is <0.1% of the total heat output from Yellowstone Caldera.
  • Preprint
    Fluid oscillations in a laboratory geyser with a bubble trap
    (Elsevier, 2018-11-10) Rudolph, Maxwell L. ; Sohn, Robert A. ; Lev, Einat
    Geysers are rare geologic features that episodically erupt water and steam. While it is understood that the eruptions are triggered by the conversion of thermal to kinetic energy during decompression of hot uids, geysers commonly exhibit a range of dynamic behaviors in-between and during eruptions that have yet to be adequately explained. In-situ measurements of temperature and pressure as well as remote geophysical techniques have revealed oscillatory behavior across a range of timescales, ranging from eruption cycles to impulsive bubble collapse events. Many geysers, including Old faithful in Yellowstone National Park, USA, are believed to have o set subsurface reservoirs (referred to as a `bubble trap') that can trap and accumulate noncondensable gas or steam entering the system. The impact of a bubble trap on the dynamic behaviors of the system, however, has not been fully established. We constructed a laboratory bubble trap and performed a series of experiments to study how uids oscillate back and forth between the eruption conduit and laterally-offseet reservoir in-between eruptions. We present a new theoretical model based on Hamiltonian mechanics that successfully predicts the oscillation frequencies observed in our experiments based on the conduit system geometry, the amount of gas that has accumulated in the bubble trap, and the amount of liquid water in the system. We demonstrate that when scaled to Old Faithful Geyser, this mechanism is capable of producing oscillations at the observed frequencies.
  • Preprint
    A model for internal oscillations in geysers, with application to Old Faithful (Yellowstone, USA)
    ( 2017-04) Rudolph, Maxwell L. ; Sohn, Robert A.
    We present a mechanical model for internal oscillations in geysers with “bubble trap” configurations, where ascending gas or vapor becomes trapped beneath the roof of a cavity that is laterally offset from the eruption conduit. We consider two cases, one in which the trapped gas behaves as an isothermal ideal gas, and one where it is treated as isenthalpic steam. In both cases the system behaves as a damped, harmonic oscillator with a resonant frequency that is sensitive to the conduit geometries and fluid volumes. We use the model to predict internal oscillation frequencies for Old Faithful geyser, in Yellowstone, USA, using conduit geometry constraints from the literature, and find that the frequencies predicted by the model are consistent with observations (~1 Hz). We show that systematic frequency increases during the recharge cycle, when the fluid volume of the system is increasing due to recharge, are consistent with either a decrease in the amount (both volume and mass) of trapped gas or vapor, a decrease in the eruption conduit area, or a combination of both.
  • Article
    Eruptions at Lone Star geyser, Yellowstone National Park, USA: 2. Constraints on subsurface dynamics
    (John Wiley & Sons, 2014-12-05) Vandemeulebrouck, Jean ; Sohn, Robert A. ; Rudolph, Maxwell L. ; Hurwitz, Shaul ; Manga, Michael ; Johnston, Malcolm J. S. ; Soule, Samuel A. ; McPhee, Darcy ; Glen, Jonathan M. G. ; Karlstrom, Leif ; Murphy, Fred
    We use seismic, tilt, lidar, thermal, and gravity data from 32 consecutive eruption cycles of Lone Star geyser in Yellowstone National Park to identify key subsurface processes throughout the geyser's eruption cycle. Previously, we described measurements and analyses associated with the geyser's erupting jet dynamics. Here we show that seismicity is dominated by hydrothermal tremor (~5–40 Hz) attributed to the nucleation and/or collapse of vapor bubbles. Water discharge during eruption preplay triggers high-amplitude tremor pulses from a back azimuth aligned with the geyser cone, but during the rest of the eruption cycle it is shifted to the east-northeast. Moreover, ~4 min period ground surface displacements recur every 26 ± 8 min and are uncorrelated with the eruption cycle. Based on these observations, we conclude that (1) the dynamical behavior of the geyser is controlled by the thermo-mechanical coupling between the geyser conduit and a laterally offset reservoir periodically filled with a highly compressible two-phase mixture, (2) liquid and steam slugs periodically ascend into the shallow crust near the geyser system inducing detectable deformation, (3) eruptions occur when the pressure decrease associated with overflow from geyser conduit during preplay triggers an unstable feedback between vapor generation (cavitation) and mass discharge, and (4) flow choking at a constriction in the conduit arrests the runaway process and increases the saturated vapor pressure in the reservoir by a factor of ~10 during eruptions.