HR: 1340h
AN: V53A-1539    [Abstracts]
TI: New acquisition techniques and statistical analysis of bubble size distributions
AU: * Proussevitch, A
EM: alex.proussevitch@unh.edu
AF: Complex Systems Research Center, University of New Hampshire, Morse Hall, Durham, NH 03824 United States
AU: Sahagian, D
EM: dork.sahagian@lehigh.edu
AF: Environmental Initiative, Lehigh University, Bethlehem, PA 18015-3005 United States
AB: Various approaches have been taken to solve the long-standing problem of determining size distributions of objects embedded in an opaque medium. In the case of vesicles in volcanic rocks, the most reliable technique is 3-D imagery by computed X-Ray tomography. However, this method is expensive, requires intensive computational resources and thus limited and not always available for an investigator. As a cheaper alternative, 2-D cross-sectional data is commonly available, but requires stereological analysis for 3-D conversion. A stereology technique for spherical bubbles is quite robust but elongated non-spherical bubbles require complicated conversion approaches and large observed populations. We have revised computational schemes of applying non-spherical stereology for practical analysis of bubble size distributions. The basic idea of this new approach is to exclude from the conversion those classes (bins) of non-spherical bubbles that provide a larger cross-section probability distribution than a maximum value which depends on mean aspect ratio. Thus, in contrast to traditional stereological techniques, larger bubbles are "predicted" from the rest of the population. As a proof of principle, we have compared distributions so obtained with direct 3-D imagery (X-Ray tomography) for non-spherical bubbles from the same samples of vesicular basalts collected from the Colorado Plateau. The results of the comparison demonstrate that in cases where x-ray tomography is impractical, stereology can be used with reasonable reliability, even for non-spherical vesicles.
DE: 3245 Probabilistic forecasting (3238)
DE: 3618 Magma chamber processes (1036)
DE: 8429 Lava rheology and morphology
DE: 8430 Volcanic gases
DE: 8439 Physics and chemistry of magma bodies
SC: Volcanology, Geochemistry, Petrology [V]
MN: Fall Meeting 2005