This past Thursday (March 21st) I took part in the Critical Thought Symposium; the issue at hand was the Yellowstone Supervolcano. My assigned role was the “U.S. Geological Survey (USGS) Volcanologist and Yellowstone Volcano Observatory (YVO) Scientist- in- Charge (SIC).” I would like to use this blog as 1) a reflection on the experience and 2) a review of a few volcanic terms and concepts for our upcoming exam.
First, I would like to offer a bit of background to the symposium situation. Yellowstone is located in the northern Rocky Mountains in Wyoming, Montana, and Idaho (McNutt and Salazar 2010). “Yellowstone National Park, justly famous for its unmatched geysers, diverse wildlife, and uniquely preserved ecologic communities, also encompasses one of Earth’s largest systems of volcanic, seismic, and hydrothermal activity” (Christiansen et al. 2010: 4).
In class we discussed various types of volcanoes. The Yellowstone system is a caldera. The Yellowstone caldera makes up roughly one third the area of Yellowstone National Park (McNutt and Salazar 2010). Three immense explosions have occurred over the past 2.1 million years; these powerful volcanic eruptions covered large portions of North America with ash and debris (Pillar). “Regional tectonics and the magmatic system combine to produce some of the highest levels of earthquake activity in the conterminous U.S. outside of California” (Christiansen et al. 2007: 8).
The caldera itself is underlain by two types of subsurface magma: basaltic magma and rhyolitic magma. As discussed in class, these two types of magma vary in their compositional nature, which in turn affects how it behaves during an eruption. Basaltic magma is relatively fluid and has very low resistance to flow; as a result, it is generally associated with small to moderate volumes of magma and relatively brief eruptions. On the other hand, rhyolitic magma is more viscous and can either “erupt effusively to produce small to large volumes of lava or explosively to produce course pumice and finer ash” (Christiansen et al. 2007: 1).
I– as the YVO SIC— was responsible for analyzing periodic updates of volcanic activity form the USGS and deciding weather to increase the volcano alert level as well as the aviation color code . The four periodic updates that I received addressed a plethora of volcanic ‘vital signs’ including deformation patterns, earthquake swarms and intensities, gas release data, and hydrothermal explosions. Seismic data, deformation data, and hydrothermal data, all contribute to helping identify any impending volcanic eruptive activity. However, given that “[n]o volcanic eruption has occurred in Yellowstone National Park or vicinity in the last 70,000 years,” it becomes very difficult to identify a threshold an impending volcanic eruption (Christiansen et al. 2007: 3). “One obstacle to accurate forecasting of large volcanic events is humanities lack of familiarity with the signals leading up to the largest class of volcanic eruptions” (Lowenstern et al. 2006).
This caveat in the data analysis proved to be very inconvenient during the symposium as policy makers and response teams continually demanded precise answers that I could not generate due to the nature of the issue at hand.
Likewise, many demanded estimates of impact ranges which are just as difficult to generate. Depending on the magnitude and nature of the hazardous geologic event, as well as the time and season when it might occur, roughly 70,000 to 100,000 people could be affected (Christiansen et al. 2007: 1). “The most violent event could affect a broader region of even continent-wide areas” (Christiansen et al. 2007: 1).
Overall, I think the symposium went went really well; it successfully simulated how difficult it is to analyze volcanic data and forecast behaviors for decision-making that will effect large numbers of the public.
Works Cited
Christiansen, Robert L., J. Lowenstern, R. B. Smith, H. Heasler, L. A. Morgan, M. Nathenson, L.G. Mastin, L.J.P. Muffler, J.E. Robinson. (2007). Preliminary Assesment of Volcanic and Hydrothermal Hazards in Yellowstone National Park and Vicinity. United States Geological Survey (USGS).
McNutt, Marcia K., and Salazar, K. (2010). Protocols for Geologic Hazards Response by the Yellowstone Volcano Observatory. United States Geological Survey (USGS).
Pillar, Greg. Queens University of Charlotte. February 14th, 2013.
Lowenstern, J. B., Smith, R. B., & Hill, D. P. (2006). Monitoring super-volcanoes: geophysical and geochemical signals at Yellowstone and other large caldera systems. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 364(1845), 2055-2072.
ENVR 102:: Introduction to Geology:: Blog 