Triggering Eruption of Large Silicic Volcanic Systems

Posted on 08.25.2015
Photo from the May 18, 1980 Mt. St. Helen’s eruption in Washington State ( The 1980 eruption  of Mt. St. Helens was a little over 1 cubic km of eruptive volume, yet had a significant impact in the region (e.g., 57 human fatalities, 12 million salmon and more than 7000 large game lost).  In comparison, the Huckleberry ridge eruption in Yellowstone (~ 2 Mya) erupted over 2000 cubic km, which makes Mt. St. Helens 1980 look tiny.

Throughout Earth’s history, there are records of very large eruptions, sometimes referred to as “supervolcanic eruptions” (depending on who you ask!). These eruptions, which are > 500 cubic km (or more than 500 times the size of Mt. St. Helens) have a severe impact on not only the region where the eruption occurs, but also across the globe. Ash clouds from eruptions of this size cover the Earth and can have a lasting effect on global climate. Understanding how and why these eruptions occur is not only import for assessing and mitigating current hazards at smaller systems, but also for understanding the evolution of volcanic systems in general.

The primary goals of this research are to constrain the physics behind how these large systems develop and better understand what causes them to eventually fail. I am particularly interested in the rheological implications of constructing systems this large. I have developed new temperature-dependent models to investigate the thermal evolution of these systems and have couple these with viscoelastic models that provide details about deformation and failure of the crustal magma chamber as it grows. This exciting work illustrates how very important temperature is for allowing these systems to grow and provides some clues as to what processes trigger their failure.

FUTURE DIRECTIONS: Up to now, model development has been focused on 2D cases. Next steps include expanding into 3D, taking into consideration variable geometries, topographic loading, tectonic stresses, heterogeneities in the crust, and pre-existing fault structures. 

COLLABORATORS: Eric Grosfils (Pomona College), Shan de Silva (OSU)

FUNDING: This work has been funded by the National Science Foundation.

Publications & Presentations from this work:
P.M. Gregg, E.B. Grosfils, S.L. de Silva, Thermomechanics of triggering the eruption of large magma reservoirs: the effects of buoyancy and magma recharge AGU Fall Meet. Suppl., 2014. INVITED

P.M. Gregg, S.L. de Silva, and A. Mucek, Viscoelastic models of resurgence at Toba Caldera, 5th International Workshop on Collapse Calderas, Taupo NZ, 2014.

A. Mucek, S. L. de Silva, and P. M. Gregg, Toba: A Resurging Caldera, 5th International Workshop on Collapse Calderas, Taupo NZ, 2014.

S.L. de Silva, and P.M. Gregg, Thermomechanical feedbacks in magmatic systems: Implications for growth, longevity, and evolution of large caldera-forming magma reservoirs and their supereruptions, J. Volcano. Geotherm. Res.,, 2014.

E.B. Grosfils, P.J. McGovern, P.M. Gregg, G.A. Galgana, D.M. Hurwitz, S. Long, S. Chestler, Elastic Models of Magma Reservoir Mechanics: A Key Tool for Understanding Planetary Volcanism. In Massironi, M., Byrne, P., Hiesinger, H., Platz, T. (Eds.), Volcanism and Tectonism across the Solar System. In: Special Publications. Geological Society, London, SP401, 2013.

P.M. Gregg, S. L. de Silva, and E. B. Grosfils, Thermomechanics of shallow magma

chamber pressurization: Implications for the assessment of ground deformation data at active volcanoes, Earth and Planetary Science Letters,, 2013.

P.M. Gregg, S. L. de Silva, E. B. Grosfils, J. Parmigiani, Catastrophic caldera-forming eruptions: Thermomechanics and implications for eruption triggering and maximum caldera dimensions on Earth, J. Volcano. Geotherm. Res., doi:10.1016/j.jvolgeores.2012.06.009, 2012.

E. B. Grosfils, P. J. McGovern, P. M. Gregg, G. A. Galgana, D. M. Hurwitz, S. M. Long, S. R. Chestler, Improving Mechanical Insight into Ring Fault Initiation and Caldera Formation via Elastic Models of Magma Reservoir Inflation, AGU Fall Meet. Suppl., 2013.

P. M. Gregg, S. L. de Silva, and E. B. Grosfils, Thermomechanics of pressurizing a shallow magma chamber: Implications for the evolution of large silicic systems, IAVCEI Scientific Assembly, 2013.

S. L. de Silva, P. M. Gregg, A thermomechanical perspective on caldera formation and classification, IAVCEI Scientific Assembly, 2013.

P. M. Gregg and S. L. de Silva, Thermomechanics of overpressurizing a shallow crystallizing magma chamber, AGU Fall Meet. Suppl., V42A-06, 2012.

S. L. de Silva, P. M. Gregg, S. Grocke, J. M. Kern, J. F. Kaiser, R. Iriarte, D. H. Burns, C. Tierney, A. K. Schmitt, W. D. Gosnold, Thermal influences on the development and evolution of large catastrophic caldera-forming magmatic systems (Invited), Eos Trans. AGU, Fall Meet. Suppl., V42A-04, 2012.

P. M. Gregg, S. L. de Silva, E. B. Grosfils, J. P. Parmigiani, Thermal-mechanics of roof failure and caldera formation in large silicic systems, Eos Trans. AGU, Fall Meet. Suppl., 2011.

P. M. Gregg, S. L. de Silva, E. B. Grosfils, J. P. Parmigiani, Development, evolution and triggering of supereruptions, Geological Society of America Mtg, Oct. 2011.

P. M. Gregg, S. L. de Silva, E. B. Grosfils, Rheological controls on roof failure in large caldera-forming eruptions, Eos Trans. AGU, Fall Meet. Suppl., 2010.