Karlstrom Leif

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Karlstrom
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Leif
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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.
  • 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.
  • Article
    History‐dependent volcanic ground deformation from broad‐spectrum viscoelastic rheology around magma reservoirs
    (American Geophysical Union, 2022-12-14) Liao, Yang ; Karlstrom, Leif ; Erickson, Brittany A.
    Geodetic timeseries suggest that volcanoes exhibit a wide range of deformation patterns. Viscoelastic deformation around crustal magma storage zones is an expected contributor to such observations, but is challenging to characterize robustly. Here we present a novel approach to modeling crustal deformation around magma reservoirs that identifies frequency‐domain signatures of viscoelastic response for temperature‐dependent crustal rheology. We develop a transfer function that links unsteady reservoir pressure forcing to surface displacement, finding that thermomechanical properties and geometry of the magmatic system are encoded in viscoelastic response on timescales where geodetic observations are routinely made. Inhomogeneous viscoelasticity is reflected by spatially variable relaxation of host rocks that results in a viscous aureole whose size depends on the frequency spectrum of forcing. We explore viscoelastic signatures of broadband pressurization episodes, identifying a history dependence of volcano deformation in which past activity influences the stress state and surface deformation patterns of future episodes.