HR: 0800h
AN: U41B-0406    [Abstracts]
TI: Inverse scattering with SKKS code waves: imaging the D" from the core side
AU: * Wang, P
EM: wangp@mit.edu
AF: EAPS, MIT, 77 Mass Ave 54-511, Cambridge, MA 02139, United States
AU: de Hoop, M V
EM: mdehoop@math.purdue.edu
AF: CCAM, Purdue University, 150 N. University Street, West Lafayette, IN 47907, United States
AU: van der Hilst, R D
EM: hilst@mit.edu
AF: EAPS, MIT, 77 Mass Ave 54-511, Cambridge, MA 02139, United States
AB: In our previous studies we developed a method for imaging heterogeneity at and near the core mantle boundary (CMB) with a generalized Radon transform (GRT) of (transverse component, broadband) ScS data, and we developed a statistical model for producing images of the D" discontinuity with variable confidence levels. In these applications the background is smooth and perturbations are represented as contrasts. Here we extend the theory to allow (known) discontinuities, such as the CMB, in the background model. The resulting imaging operator, which is formally not a GRT, can be exploited to scan the CMB discontinuity from the core side using the (radial component) wavefield of the underside SKKS reflection. We demonstrate furthermore that the SKKS phase can be used, either alone or along with ScS, for the imaging of lowermost mantle structure and, in particular, the D" discontinuity. Synthetic seismograms calculated with the SEM method are used to test the performance of our approach. As a proof of concept, we transform ~18,000 radial component SKKS waveforms into image gathers of a CMB patch beneath Central America. The SKKS image gathers and image traces are in good agreement with the image traces obtained from the GRT transform of ScS data. We furthermore do the joint inversion of ScS and SKKS data and obtain images with better resolution, in particular of interfaces that are difficult to detect with topside ScS reflections.
DE: 3630 Experimental mineralogy and petrology
DE: 3924 High-pressure behavior
DE: 7207 Core (1212, 1213, 8124)
DE: 7208 Mantle (1212, 1213, 8124)
DE: 8124 Earth's interior: composition and state (1212, 7207, 7208, 8105)
SC: Union [U]
MN: 2007 Fall Meeting