Feb 2, 2004 PART I: Quantifying the Volcanic Emissions of Trace Elements to the Atmosphere: Ideas Based on Past Studies PART II: Santa María and Santiaguito: a Superb Field Volcanological Laboratory by W I Rose, Otoniel Matias, Rüdiger Escobar Wolf

Professor Bill Rose will give two related talks at the Remote Sensing Seminar on Monday (3 pm, U113). They will include

* A presentation that he was invited to give at the December meeting of the American Geophysical Union, as part of a joint Atmospheric Sciences/Volcanology session "Quantifying the Volcanic Emissions of Trace Elements to the Atmosphere: Ideas Based on Past Studies"

* An updated and expanded presentation on volcanoes research in Guatemala: "Santa María and Santiaguito: a Superb Field Volcanological Laboratory"

Refreshments will be served before the seminar. Details on the presentation are provided in the abstracts below.
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Two seminars (titles below and above)

by W. I. Rose
GMES Department, Michigan Tech

4 pm, Monday, February 2
U113, M&M Building

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PART I:
Quantifying the Volcanic Emissions of Trace Elements to the
Atmosphere: Ideas Based on Past Studies

Extensive data exist from volcanological and geochemical studies about exotic elemental enrichments in volcanic emissions to the atmosphere. Advanced, highly sensitive techniques of analysis are needed to detect low concentrations of some minor elements, especially during major eruptions. I will present data from studies done during low levels of activity (incrustations and silica tube sublimates at high temperature fumaroles, from SEM studies of particle samples collected in volcanic plumes and volcanic clouds, from geochemical analysis of volcanic gas condensates, from analysis of treated particle and gas filter packs) and a much smaller number that could reflect explosive activity (from fresh ashfall leachate geochemistry, and from thermodynamic codes modeling volatile emissions from magma). This data describes a highly variable pattern of elemental enrichments which are difficult to quantify, generalize and understand. Sampling in a routine way is difficult, and work in active craters has heightened our awareness of danger, which appropriately inhibits some sampling. There are numerous localized enrichments of minor elements that can be documented and others can be expected or inferred. There is a lack of systematic tools to measure minor element abundances in volcanic emissions. The careful combination of several methodologies listed above for the same volcanic vents can provide redundant data on multiple elements which could lead to overall quantification of minor element fluxes but there are challenging issues about detection. For quiescent plumes we can design combinations of measurements to quantify minor element emission rates. Doing a comparable methodology to succeed in measuring minor element fluxes for significant eruptions will require new strategies and/or ideas.

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PART II:
Santa María and Santiaguito: a Superb Field Volcanological
Laboratory

by W I Rose, Otoniel Matias, Rüdiger Escobar Wolf

One of three actively erupting volcanoes in Guatemala, Santa María/Santiaguito has been the site of geological work for more than 100 years and is still a magnet for scientists. Santa María's 1902 crater offers unusual access to its gradually changing sequential eruptive products over the past 25 ka. Preservation of composite cone lavas and fragmental deposits is excellent. The mixed magma plinian 1902 eruption has well preserved fall deposits over much of western Guatemala and Southern Mexico and spans a compositional gap from basaltic andesite to dacite. The Santiaguito dome activity has been continual since 1922 with an oscillating eruption rate. A variety of eruption styles have been observed, including endogenous dome extrusion, exogenous block lava flows, block and ash flows, lahars and floods and frequent (several times a day) small vertical ash eruptions. The volcano is accessible by ground routes which are no more than a few hours walk at relatively low altitudes from good roads, and including an unusual summit perspective. There is a long context of field observations there, enabling long term studies of dome phenomena to be placed in a context. There is a volcano observatory and an active observer who provides daily observations. Monitoring efforts are planned to improve. The morning weather is usually clear, in spite of a climate that has frequent fog, and this aids in both ground and satellite remote sensing observations. The volcano has active fumaroles and a gas plume with unusual chemistry. A geothermal drill site near Zunil, a few km NE of Santa María offers insight into the subsurface geology. The volcano is located upslope from the Boca Costa, an extraordinarily productive area of commercial agriculture which has a growing population and provides important foreign exchange income for Guatemala. So the volcano's future activity and the associated ever changing volcanic hazards of the area are a priority for government agencies.