HR: 11:50h
AN: G52A-07    [Abstracts]
TI: Magma Chamber Geometry at Mauna Loa Volcano From InSAR and GPS 2002-2004
AU: * Yun, S
EM: shyun@stanford.edu
AF: Stanford University, Geophysics Department Stanford University, Stanford, CA 94305 United States
AU: Amelung, F
EM: amelung@rsmas.miami.edu
AF: University of Miami, 4600 Rickenbacker Causeway , Miami, FL 33149 United States
AU: Miklius, A
EM: asta@usgs.gov
AF: U.S. Geological Survey, Hawaiian Volcano Observatory U.S. Geological Survey, Kilauea, HI 96722 United States
AU: Walter, T
EM: twalter@rsmas.miami.edu
AF: University of Miami, 4600 Rickenbacker Causeway , Miami, FL 33149 United States
AU: Segall, P
EM: segall@pangea.stanford.edu
AF: Stanford University, Geophysics Department Stanford University, Stanford, CA 94305 United States
AB: We model crustal deformation at Mauna Loa volcano using boundary element methods constrained by Synthetic Aperture Radar Interferometry (InSAR) and Global Positioning System (GPS) data. 80 interferograms are stacked to reduce atmospheric noise for 5 different look angles (2 ascending and 3 descending with look angles from 23.5 to 43.5 degrees) from the Radarsat satellite. The overall time span of the interferograms is January 2002 - May 2004, and the average line-of-sight velocities are from 10 cm/year (ascending beam 6) to 18 cm/year (descending beam 6). The GPS data are averaged to match the effect of stacking the InSAR data. We fit the five interferograms with one planar dike-like and one spherical magma chamber that are interconnected and share the same excess magma pressure. Simulated annealing inversion solves for the excess pressure and the geometry of the deformation source. The estimated excess pressure is about 7 MPa, and the spherical magma chamber is estimated to be at a depth of about 3.6 km. The excess pressure constrains the radius of the spherical chamber, which is estimated to be about 2 km. The main portion of the dike, which aligns with Mauna Loa's southwest rift zone, is located below (8km) and southwest of the spherical chamber, indicating that magma may have migrated toward the northeast to an equidimensional chamber below the summit of Mauna Loa. The volume changes in the dike and in the spherical chamber are 52 million cubic meters and 9.7 million cubic meters respectively. The radius of the spherical chamber is being adjusted on the basis of modeling with a finite spherical geometry, because the point source (e.g. Mogi) approximation does not hold well for such a large ratio of radius to depth.
DE: 1240 Satellite geodesy: results (6929, 7215, 7230, 7240)
DE: 3260 Inverse theory
DE: 6924 Interferometry (1207, 1209, 1242)
DE: 8145 Physics of magma and magma bodies
DE: 8485 Remote sensing of volcanoes
SC: Geodesy [G]
MN: Fall Meeting 2005