Research Opportunity Description
For over 30 years, the USGS Alaska Volcano Observatory has sustained an airborne volcanic gas monitoring program to help track activity at hazardous volcanoes in the Cook Inlet region of Alaska. The resulting gas emissions dataset is unprecedented in scope and duration worldwide; included are measurements of sulfur-containing gases, carbon dioxide (CO2), and halogen species during major eruptions of Redoubt Volcano (1989, 2009), Mount Spurr (vent at Crater Peak, 1992), Augustine Volcano (2006), two intrusions at Iliamna Volcano (1996, 2012), and annual measurements during quiet periods. These efforts in Alaska have led to novel insights that have been broadly applied to explosive arc volcanoes globally, including the strong influence gas-water-rock ‘scrubbing’ reactions (Doukas and Gerlach, 1995), and the first observation of a CO2-rich eruption precursor at an intermediate-composition arc volcano (Werner et al. 2013). What remains, however, is a way to link volcanic gas-based monitoring data to magmatic processes at depth.
Pre-eruptive magmatic volatile contents offer robust ways of constraining degassing depths and eruption mass—both critical to better constraining the hazards associated with explosive volcanism. Melt inclusion studies provide the most robust means to constrain these, however many are performed in olivine or quartz minerals, which are more easily prepared but typically found in endmember basalt or rhyolite rock compositions. As most explosive volcanism in Alaska is intermediate in composition and lacks these mineral phases, there exists a significant knowledge gap in interpreting gas-based monitoring data for a large number of the volcanoes. While mineral phases common to intermediate systems such as pyroxene and plagioclase have melt inclusions that may be analyzed, their preparation is substantially more difficult and time consuming, ultimately limiting our knowledge of these systems.
For historical Cook Inlet eruptions, there have been only a handful of such studies, all of which only analyzed a small number of inclusions (Roman et al., 2006; Gerlach et al.1994; Webster et al., 2010). These studies only include Spurr and Augustine Volcano, and only the later includes petrologic estimates for a full suite of magmatic volatile. These studies, while important, are now dated and do not incorporate major advancements in our understanding of melt inclusions including post entrapment crystallization corrections and accounting for CO2 trapped in shrinkage bubbles.
The successful candidate will document the pre-eruptive magmatic volatile contents of historically active Cook Inlet volcanoes including Mount Spurr, Redoubt Volcano, Iliamna Volcano, and Augustine Volcano. We expect this research to focus on preparation and analysis of melt inclusions especially from historical eruption samples and augmenting existing melt inclusion studies. The project should focus on melt inclusions hosted within dominant mineral phases from these systems and provide innovative advancements to make their preparation and analysis more efficient. Other petrologic means of estimating magmatic volatile contents, including but not limited to mineral hygrometers and numerical modeling are also encouraged.
Results will inform retrospective analysis of volcanic gas emission data over the last 30 years which includes: 4 eruptions, periods of magmatic intrusions, and background gas emissions. Topics to consider could include: petrologic estimates of eruption mass compared to deformation and geologic constraints, depths of magma storage and degassing, along arc trends in magmatic volatiles, possible crustal geology contributions to volatile budgets, mineralization processes at active volcanoes, and magmatic volatile controls on eruptive behavior. These results should better prepare the Alaska Volcano Observatory to respond to the next Cook Inlet eruption by fully utilizing active gas emission measurements.
Interested applicants are strongly encouraged to contact the Research Advisor(s) early in the application process to discuss project ideas.
References
Doukas, M. P., 1995, A compilation of sulfur dioxide and carbon dioxide emission-rate data from Cook Inlet volcanoes (Redoubt, Spurr, Iliamna, and Augustine), Alaska during the period from 1990 to 1994: U.S. Geological Survey Open-File Report 95-55, 15 p.
Gerlach, T.M., Westrich, H.R., Casadevall, T.J., and Finnegan, D.L., 1994, Vapor saturation and accumulation in magmas of the 1989–1990 eruption of Redoubt Volcano, Alaska, Journal of Volcanology and Geothermal Research, v. 62, n. 1-4, p. 317–337.
Roman,D.C., Cashman, K.V., Gardner, C.A., Wallace, P.J., and Donovan, J.J., 2006, Storage and interaction of compositionally heterogeneous magmas from the 1986 eruption of Augustine Volcano, Alaska: Bulletin of Volcanology, Nov 2005, v. 68, n. 3, p. 240-254, doi: 10.1007/s00445-005-0003-z.
Webster, J.D., Mandeville, C.W., Goldoff, B., Coombs, M.L., and Tappen, C., 2010, Augustine Volcano—The influence of volatile components in magmas erupted A.D. 2006 to 2,100 years before present, U.S. Geological Survey Professional Paper 1769, p. 383–423.
Werner, C., Kelly, P.J., Doukas, M., Lopez, T., Pfeffer, M., McGimsey, R., and Neal, C., 2013, Degassing of CO2, SO2, and H2S associated with the 2009 eruption of Redoubt Volcano, Alaska: Journal of Volcanology and Geothermal Research, v. 259, p. 270-284, doi:10.1016/j.jvolgeores.2012.04.012
Proposed Duty Station(s)
Anchorage, Alaska
Areas of PhD
Geology or related fields (candidates holding a Ph.D. in other disciplines, but with extensive knowledge and skills relevant to the Research Opportunity may be considered).
Qualifications
Applicants must meet the following qualifications: Research Geologist.
(This type of research is performed by those who have backgrounds for the occupations stated above. However, other titles may be applicable depending on the applicant's background, education, and research proposal. The final classification of the position will be made by the Human Resources specialist.)
