HR: 17:45h
AN: V24B-08    [Abstracts]
TI: The Present and Future of Volcano Research Drilling
AU: * Eichelberger, J C
EM: eich@gi.alaska.edu
AF: Alaska Volcano Observatory, Geophysical Institute University of Alaska Fairbanks, Fairbanks, AK 99775 United States
AB: The success of the Unzen Scientific Drilling Project (USDP) in reaching and sampling the conduit of Unzen Volcano demonstrates that: (1) Directional drilling is applicable to volcanic systems; (2) Geophysical monitoring during eruption and high-resolution surveys afterward provide a reliable view of the magma pathway; (3) At least some of our ideas about syneruptive magmatic behavior appear to be confirmed through this glimpse of new magma emplaced under a load of more than 30 MPa, containing melt that had lost less than half its water; and (4) Temperatures are relatively low, indicating stronger hydrothermal dissipation of magmatic heat than anticipated. There remains, of course, a great deal more to be learned about the conduit of Unzen from detailed analysis of the core samples and interpretation of drilling and logging data. Further analysis will determine whether we have opened a new door to understanding volcanoes or engaged in a one-time trip to the "Moon". While the cost of USDP is unprecedented in volcanology, it is less than one percent of the cost of damage that Unzen did in the 1990-1995 eruption. The USDP conduit data point lies toward one end (excepting very large continental systems) of a continuum in terms of repose time. Unzen has a repose period of a hundred or more years. It is therefore not surprising that the conduit of Unzen is a warm ribbon in a cold edifice. Higher temperatures are to be expected in systems with shorter repose times. This is important because the thermal and mechanical state of the edifice will likely affect the rise of new magma; associated precursory seismicity, deformation, and thermal and gas emission; and subsequent eruptive behavior. Other parameters are of interest as well, such as how recharge from a crater glacier or lake affects the hydrologic regime of a conduit, with resultant phreatomagmatic and hydrothermal activity. And to what extent might forecasts be improved by placing geophysical and geochemical instruments near or even directly in the magma pathway during repose? The fact is that many characteristics of the conduit environment in active systems, characteristics that we have previously only guessed at, can now be measured directly. If we believe that advances in understanding volcanic systems will save lives, then we should drill on, rather than being content with repetitive surface studies of volcanoes. Continued research drilling should be targeted on volcanoes where the risk of eruption to populations is high and where results will span the parameter space of conduit environments. Some of this drilling may yield not just advances in basic science and in eruption forecasting, but geothermal energy as well.
DE: 8419 Eruption monitoring (7280)
DE: 8434 Magma migration
DE: 8494 Instruments and techniques
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2004 AGU Fall Meeting