Application of 2.5D Finite Difference Tomographic Waveform Imaging to the Cascadia 1993 data set
Abstract
We apply the 2.5D full waveform tomographic imaging technique of Roecker et al. (2010) to data from the IRIS-PASSCAL Cascadia 1993 (CASC93) experiment conducted across central Oregon (Nabelek et al., 1993). Our main objective was to benchmark this imaging approach by comparing results with those previously determined Rondenay et al. (2001) using a ray-based scattering-migration technique. We adopt a step-wise approach in which we first solve for a background model by fitting phase offsets, and then mimic standard receiver function migration by back projecting deconvolved horizontal records of the P coda into the background. Interface positions are then used in an iterative way to refine the background model prior to waveform inversion. An unanticipated issue of importance in receiver function migration using this technique is that while the half-differential (Hankel) operator is not important for waveform morphology in forward propagation it is essential for the back propagated wave. The most important result of the model we obtain from waveform inversion is that it retains most of the first order features from the Rondeney et al. (2001) image, but with significantly smaller variations in wavespeed. We anticipate that these results will allow a better constrained model of subduction-related metamophism.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2010
- Bibcode:
- 2010AGUFM.S31A2043R
- Keywords:
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- 0520 COMPUTATIONAL GEOPHYSICS / Data analysis: algorithms and implementation;
- 7240 SEISMOLOGY / Subduction zones;
- 7270 SEISMOLOGY / Tomography