HR: 0800h
AN: S41C-1006    [Abstracts]
TI: Global P-wave tomography and information theory
AU: * soldati, g
EM: soldati@ingv.it
AF: INGV, via di vigna murata 605, Rome, 00100 Italy
AU: Boschi, l
EM: boschi@tomo.ig.erdw.ethz.ch
AF: ETH, schaffmattst. 30, Zurich, 8093 Switzerland
AB: Rapidly growing computer power allows to perform in relatively short times very large numbers of global tomographic inversions. We study the response of global tomographic images of P-velocity in the Earth's mantle (based upon the ISC database) to changes in the regularization criterion and in the number of dimensions in the solution space (i.e. number of model coefficients). We use the L-curve method to visualize the relation between model roughness (determined by regularization) and data fit, at any given parameterization level; this allows us to identify a range of acceptable values for the damping parameter. We then use the corrected Akaike information criterion to establish the optimal number of free parameters for our solution models. We find that ISC teleseismic P-travel-time data are likely to be over-fit if voxels of lateral extent > 5° are used to parameterize the mantle--with a uniform grid (the picture might change if grid density varies laterally, based on ray-path coverage). We analyze our results in more detail at three selected levels of parameterization (10°, 5° (our preferred model at this point) and 3°), focusing on the model resolution matrix and episodes of fictitious coupling between model coefficients.
DE: 3260 Inverse theory
DE: 7208 Mantle (1212, 1213, 8124)
DE: 7270 Tomography (6982, 8180)
SC: Seismology [S]
MN: Fall Meeting 2005