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Gravity inversion in spherical coordinates using tesseroids Leonardo Uieda Valéria C. F. Barbosa

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vs Cartesian Spherical

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Existing inversion with tesseroids (Chaves and Ussami, 2013) ● Geoid height anomalies ● Space domain ● Regularization: – Depth-weighted Minimum Volume – Similarity to seismic tomography

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Adapt Planting anomalous densities (Uieda and Barbosa, 2012)

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Planting anomalous densities ● Space domain ● Multicomponent: gravity + gradients ● Non-conventional inversion – Growth algorithm – No linear systems – Efficient sensitivity computations

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Seed

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Synthetics ● Possible applications ● Advantages ● Shortcomings

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Lineament with dense rocks (magmatic) Inspired by Chad lineament model (Braitenberg et al, 2011)

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After Braitenberg et al (2011)

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After Braitenberg et al (2011)

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10º N 300 kg.m-3 2º 8km top=1 km

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gzz At 20 km

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Seeds

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observed predicted

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What if height=120 km?

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at 120 km at 20 km

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observed predicted

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at 120 km at 20 km

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Even higher height=270 km

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at 270 km at 120 km

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observed predicted

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at 270 km at 120 km

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Magmatic underplating Inspired by model of the Paraná basin by Mariani et al (2013)

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After Mariani et al (2013)

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After Mariani et al (2013)

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10º N 200 kg.m-3 15 km 5º 10º top=30 km

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gzz at 250 km

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Seed

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What if I use wrong density?

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150 kg.m-3 250 kg.m-3

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In conclusion

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for tesseroids

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Works well

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height matters 20km 250km

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correct dense correct dense

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Future ● Combinations of tensor components ● Dipping sources (subducting plate) ● Real data (open for collaboration)

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OPEN SOURCE fatiando.org github.com/leouieda/egu2014

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Extra

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(Hypothetical) Mantle Plume Inspired by synthetics in Chaves and Ussami (2013)

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After Chaves and Ussami (2013)

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top=100 km 200 km 700 km 2º -50 kg.m-3

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gzz at 250 km

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Seed

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Joint gz + gzz?

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Same seed

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gz gzz

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gzz Joint

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gzz Joint

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single vs joint