Inversion for sources of crustal deformation and gravity change at the Yellowstone caldera

Journal Article · Sat Nov 10 00:00:00 EST 1990 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/JB095iB12p19839· OSTI ID:5195464

Vasco, D W; Taylor, C L ^[1]; Smith, R B ^[2]

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1. Geophysics Lab., Hanscom AFB, MA (USA)
2. Univ. of Utah, Salt Lake City (USA)

The Yellowstone caldera was formed in the latest of three explosive eruptions of rhyolites and ash flow tuffs totaling 3,700 km{sup 3} at 2, 1.2, and 0.6 m.y. before present. Its youthful volcanic history, widespread hydrothermal activity, intense seismicity, and extremely high heat flow, in excess of 30 times the continental average, marks the Yellowstone volcanic system as a giant caldera at unrest. Orthometric height increases of the caldera of up to 76 cm, measured from precise leveling surveys from 1923 to 1975-1977, were inverted to determine volume expansion source models for the caldera-wide deformation. For the 1923 to 1977 uplift episode, two regions of expansion were found: (1) in the northern part of the caldera near the Sour Creek resurgent dome of {approximately}0.37 km{sub 3}, and (2) in the southern part of the caldera, near the Mallard Lake resurgent dome of {approximately}0.41 km{sub 3}. Both bodies occur in the upper crust from near-surface depths to 6.0 km, but the largest volume expansions were found in the 3.0-6.0 km depth range. The southern caldera source volume, near the Mallard Lake dome, may extend down to 9.0 km. From 1976 to 1987, nearly simultaneous measurements of elevation and gravity changes were made on a profile across the northern caldera during a period of net uplift. Models of the temporal gravity variation infer that the volume increase for the northern caldera source must lie above 9.0 km and involved a density perturbation greater than +0.002 g/cm{sup 3}. The modeled volumetric sources are in the same general locations as bodies of low P wave velocities, high seismic attenuation, and large negative Bouguer gravity anomalies. It is likely that the modeled volumetric increases were caused by migration of magmas and/or the introduction of large volumes of hydrothermal fluids into the upper crust.

• OSTI ID: 5195464
• Journal Information: Journal of Geophysical Research; (United States), Vol. 95:B12; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
CALDERAS
GROUND UPLIFT
YELLOWSTONE NATIONAL PARK
AGE ESTIMATION
ATTENUATION
CONTINENTAL CRUST
DEFORMATION
DENSITY
DEPTH
EXTRUSION
GEOLOGIC HISTORY
GEOLOGIC MODELS
GEOLOGIC STRUCTURES
GEOPHYSICAL SURVEYS
GRAVITY SURVEYS
HEAT FLOW
HEIGHT
HYDROTHERMAL SYSTEMS
MAGMA
RESERVOIR FLUIDS
RHYOLITES
SEISMIC P WAVES
SEISMICITY
TUFF
VARIATIONS
VOLUME
DIMENSIONS
EARTH CRUST
ENERGY SYSTEMS
FABRICATION
FLUIDS
GEOTHERMAL SYSTEMS
IGNEOUS ROCKS
MATERIALS WORKING
PHYSICAL PROPERTIES
PUBLIC LANDS
ROCKS
SEISMIC WAVES
SURVEYS
VOLCANIC ROCKS
580000* - Geosciences