mislocation important for body waves p in particular

Mislocation important for body waves P in particular

How do we handle locations in tomography?

€

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)