HR: 08:05h
AN: V51F-01 INVITED    [Abstracts]
TI: Source Modeling and Seismic-Volcano Implications of the 2004-2007 Accelerated Deformation at Yellowstone Caldera
AU: * Chang, W
EM: wchang@earth.utah.edu
AF: University of Utah, WBB706 135 S 1460 E, Salt Lake City, UT 84112, United States
AU: Smith, R
EM: rbsmith@earth.utah.edu
AF: University of Utah, WBB706 135 S 1460 E, Salt Lake City, UT 84112, United States
AU: Wicks, C
EM: cwicks@usgs.gov
AF: U.S. Geological Survey, MS 977, Menlo Park, CA 94025, United States
AU: Farrell, J
EM: jfarrell@earth.utah.edu
AF: University of Utah, WBB706 135 S 1460 E, Salt Lake City, UT 84112, United States
AU: Puskas, C
EM: cmpuskas@earth.utah.edu
AF: University of Utah, WBB706 135 S 1460 E, Salt Lake City, UT 84112, United States
AB: The youthful Yellowstone volcanic system is characterized by extensive earthquakes, episodes of cyclical uplift and subsidence, extraordinarily high heat flow, and widespread hydrothermal activity. In mid-2004, deformation of the 45-km-wide by 75-km-long Yellowstone caldera, measured by continuously operating GPS and InSAR, unexpectedly changed from subsidence to uplift at rates of up to 6.6 cm/yr that is three to four times faster than earlier deformation episodes. This pronounced uplift has continued to the time of this abstract submission, fall 2007, and was also accompanied by unusual subsidence of up to 4 cm/yr across the northwest caldera rim near the Norris Geyser Basin. Corresponding horizontal motions of 0.8-2.2 cm/yr and 0.7-2.0 cm/yr directed outward from the caldera and inward to the Norris area, respectively. Source modeling of the deformation data revealed an expanding sill-like structure 10 km beneath the caldera with a volumetric expansion rate of 0.11 km³/yr, consistent with the amount of magma required to supply the observed high heat flow of the caldera, and a contracting tabular body 8 km under the Norris area with a volumetric contraction rate of 0.01 km³/yr. The modeled expanding sill overlaps with the top of a tomographically imaged magma body, implying that the accelerated uplift is related to the inflation from the shallowest part of the magma chamber. The inflation of the caldera sill can furthermore induce dilatational strain in the surrounding volcanic rocks beneath the northern caldera rim, causing hydrothermal fluids to migrate into the caldera that can depressurize the Norris hydrothermal systems and cause the ground to subside. We also evaluate the elastic and viscoelastic stress evolution of this accelerated uplift to model the temporal changes of Columb failure stress on adjacent faults. The results will help us understand the interaction between the volcanic system and earthquake occurrence of the Yellowstone region.
DE: 8130 Heat generation and transport
DE: 8137 Hotspots, large igneous provinces, and flood basalt volcanism
DE: 8419 Volcano monitoring (7280)
DE: 8440 Calderas
DE: 8488 Volcanic hazards and risks
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting