HR: 0800h
AN: P11A-0950    [Abstracts]
TI: Lava Flows on Olympus Mons, Mars: Estimates of Flow Speeds and Volume Fluxes from MOC, THEMIS and MOLA Data
AU: * Bruno, B C
EM: bruno@higp.hawaii.edu
AF: University of Hawaii (SOEST/HIGP), 1680 East West Road, Honolulu, HI 96822 United States
AU: Fagents, S A
EM: fagents@higp.hawaii.edu
AF: University of Hawaii (SOEST/HIGP), 1680 East West Road, Honolulu, HI 96822 United States
AU: Feirstein, E J
EM: edenf@hawaii.edu
AF: University of Hawaii (SOEST/HIGP), 1680 East West Road, Honolulu, HI 96822 United States
AU: Pilger, E
EM: pilger@higp.hawaii.edu
AF: University of Hawaii (SOEST/HIGP), 1680 East West Road, Honolulu, HI 96822 United States
AU: Rowland, S
EM: scott@higp.hawaii.edu
AF: University of Hawaii (SOEST/HIGP), 1680 East West Road, Honolulu, HI 96822 United States
AU: Garbeil, H
EM: harold@higp.hawaii.edu
AF: University of Hawaii (SOEST/HIGP), 1680 East West Road, Honolulu, HI 96822 United States
AB: This research aims at characterizing the eruptive behavior of Olympus Mons and other major volcanoes in the Tharsis region on Mars. We are particularly interested in estimating flow speeds and volume fluxes for flows emanating from vents at various locations between the summit and the basal scarp. Our methodology involves: (1) identifying lava tubes and channels that are relatively pristine and undegraded from high-resolution (3-10m/pixel) MOC images and lower-resolution, broader-coverage (18-19m/pixel) THEMIS visible images; (2) reprojecting the MOC images into a planetocentric, simple-cylindrical coordinate system to facilitate comparison with the Mars Orbiter Laser Altimeter (MOLA) digital elevation data; (3) measuring the width and depth of tubes and channels on the processed images; (4) constructing a global slope map of Mars from the interpolated MOLA 1/128$\deg$ DEM and using it to determine ground slopes along the lava tubes and channels of interest; (5) calculating flow speeds and total volume fluxes from the Jeffrey's equations based on assumed values of lava viscosity and density and a range of plausible values for lava depth (which has an upper bound of tube/channel depth); and (6) identifying correlations between flow speeds and/or total volume fluxes and the presence of tubes vs. channels. A key challenge lies in making accurate measurements of the depths of lava tubes and channels. Flow speed and total volume flux respectively have quadratic and cubic dependences on lava flow depth (which is estimated from tube or channel depth), so any errors in depth estimates are not readily forgiven. We are currently exploring different methodologies to get the best depth estimates. To date, we have width and depth estimates of 42 relatively narrow (typically $<$100m diameter) lava tubes and channels from MOC images near the summit and on the flanks of Olympus Mons. We will expand this dataset to include larger lava tubes and channels on Olympus Mons from THEMIS images, as well as tubes and channels of various sizes on the other major Tharsis volcanoes (Arsia, Ascraeus and Pavonis Mons) from both MOC and THEMIS images.
DE: 8414 Eruption mechanisms
DE: 8429 Lava rheology and morphology
DE: 8450 Planetary volcanism (5480)
DE: 5480 Volcanism (8450)
DE: 6225 Mars
SC: Planetary Sciences [P]
MN: 2004 AGU Fall Meeting