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Research Published on 2004-10 Deformation and 2008-09 Swarm

University of Utah researchers recently published two new articles in the journal Geophysical Research Letters that emphasize the active nature of the Yellowstone volcanic and hydrothermal system. The first article by Ph.D. candidate Jamie Farrell and colleagues summarizes research on the Yellowstone Lake swarm of late 2008 and early 2009. Besides a full summary of the characteristics of the swarm, they describe how the largest, deepest earthquake had an unusual volumetric (explosive) behavior, consistent with movement of fluid from depth and into the shallower hydrothermal system (less than 4 km or 3 miles deep).

In addition, careful analysis of the Yellowstone continuous GPS data revealed notable horizontal ground extension (up to 7 mm or 0.3 inches) on the surface consistent with expansion of a fracture beneath the lake. This sort of behavior was similar to Yellowstone's largest swarm in 1985 on the west side of the Yellowstone Plateau and may be more common than thought. The authors suggest that this style of behavior is key to understanding hydrothermal explosions, large earthquakes, and even volcanic eruptions.

The other paper, written by Assistant Professor Wu-Lung Chang of the National Central University of Taiwan and University of Utah Research Associate, and colleagues at the University of Utah discuss the temporal properties of the accelerated caldera uplift between 2004 and 2010, focusing on the period of uplift decline. As in their earlier paper, the authors modeled the uplift and concluded that it was due to expansion of a horizontal volcanic sill near the top of the magma chamber (7-10 km or 4-6 miles) beneath the surface. In this new paper they conclude that since 2006 the ground deformation pattern revealed a temporal reduction of the uplift that subsided from southeast to northwest across the caldera. This motion could be due to lower volumes of deep recharge of magma and hydrous fluids or could be due to pressure release related to the 2008 Yellowstone Lake and the recent 2010 Madison Plateau earthquake swarms.

Reference Chang, W., R.B. Smith, C. Wicks, C. Puskas, and J. Farrell, 2007, Accelerated uplift and source models of the Yellowstone caldera, 2004-2006, From GPS and InSAR observations, Science 9 November 2007: Vol. 318. no. 5852, pp. 952 - 956 DOI: 10.1126/science.1146842 Chang, W.-L., Smith, R.B., Farrell, J., and Puskas, C.M., 2010, An extraordinary episode of Yellowstone caldera uplift, 2004-2010, from GPS and InSAR observations: Geophysical Research Letters, v. 37, L23302, doi:10.1029/2010GL045451 Farrell, J., Smith, R.B., Taira, T., Chang, W.-L., and Puskas, C.M., 2010, Dynamics and rapid migration of the energetic 2008-2009 Yellowstone Lake earthquake swarm: Geophys. Res. Lett., 37, L19305, doi:10.1029/2010GL044605. Waite, G.R. and Smith, R.B., 2002, Seismic evidence for fluid migration accompanying subsidence of the Yellowstone Caldera: Journal of Geophysical Research, v. 107, no. B9, p. 2177, 10.1029/2001JB000586

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