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Computer Aided Tomography
Tomos: cut (Gr.)
Extensively used to find 3D structure from surface measurements (X-ray, sound, seismic waves)
Principles of tomography
Seismic tomography
• Earthquake source & receivers
• 3D perturbation vs 1D Earth model (PREM)
• Difficulties:– Curved raypaths that depend on velocity– Poor distribution of earthquakes and receivers– Lack of high precision in earthquake source and
time.
Mantle tomography
• E.g., Bijwaard, Spakman, Engdahl, 1999.
Subducting Farallonslab
Montelli et al., Science, 303, 2004
Plume clusters or ‘superplumes’
Montelli et al., Science, 303, 2004
Montelli et al., Science, 303, 2004
Subduction zones