Mislocation important for body waves P in particular
How do we handle locations in tomography?
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δt = Aδh + Bδv
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P • δt = P • Bδv
P • A = 0
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δt = Aδh → δt1 = δt − Aδ ˆ h
δt1 = Bδv → c1 = Bδ ˆ v
δt1 − c1 = Aδh → δt2
Iterative Relocation
Projection€
δt = γA B[ ]γ −1δh
δv
⎡
⎣ ⎢
⎤
⎦ ⎥
Joint Inversion
Do numerical experiment• Make synthetic data for a known model but with event
locations perturbed
• Invert using the different relocation schemes and compare final models with original models
• Use P data (so upper mantle is not well-constrained)
Model made using projection
Original model
Model from iterative relocation
Original model
20s P waves ordered by distance, 20--100 degrees
After clustering….
Diffracted Waves
• Coverage of CMB poor in existing models
• Diffracted waves travel along base of mantle
• Lots of data
Coverage with ScS-S
Need to correct for effect of crust
(don’t use station corrections)
Shear velocity -- +-1% isovelocity surfaces
Includes S and SS cluster analysis data
The effect of not using surface waves on the recovery of near-surface structure
Large anomalies
Still large--don’t see subduction zones
Little of cratons left
Scale change! Subduction!
Possible slabs
Superplumes or plume groups
Improves resolution of structure near the base of the mantle
Shear velocity -- +-1% isovelocity surfaces
Includes S and SS cluster analysis data
70%
80%
50%
(without diffracted)