HR: 1340h
AN: S13D-1092    [Abstracts]
TI: Whole Earth Tomographic Models: a Resolution Analysis
AU: * Soldati, G
EM: soldati@ingv.it
AF: Istituto Nazionale di Geofisica e Vulcanologia, via di Vigna Murata, 605, Rome, 00143 Italy
AU: Boschi, L
EM: boschi@tomo.ig.erdw.ethz.ch
AF: Institute of Geophysics ETH Hoenggerberg HPP, Schafmattstr. 30, Zuerich, CH-8093 Switzerland
AB: The evaluation of the resolution of global tomographic models of the Earth through synthetic tests has been proven to have intrinsic limits, strongly depending on the choice of the "input model". We have evaluated the resolution of whole-Earth structure achieved by compressional wave travel time data from the ISC bulletins, computing directly the model resolution matrix (e.g., Menke, 1989), i.e. the operator that relates output and input model in any synthetic test. The knowledge of R permits to detect what fictitious trade-offs (aliasing, leaking) occur, in the least-squares inversion, between any couple of model coefficients. While the robustness of mantle images is confirmed, the problem of mapping the Earth's CMB and core is inherently unstable: we found severe fictitious trade-offs within the CMB and outer core, or between the two, suggesting that a reliable modeling of those regions should take into account further complexities of the real Earth like the high-frequency structure in the D'' and the full mantle anisotropy. Our computational resources and the speed with which the inversions are carried out (few minutes) on a shared-memory, multiprocessor computer makes a refinement of our parameterization feasible.
DE: 8180 Tomography
DE: 7260 Theory and modeling
DE: 7207 Core and mantle
SC: Seismology [S]
MN: 2004 AGU Fall Meeting