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Africa’s Crustal Architecture Inferred from Probabilistic and Perturbational Inversion of Ambient Noise: ADAMA
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  • Tolulope Olugboji,
  • Siyu Xue,
  • Jean-Joel Legre,
  • Yuri Tamama
Tolulope Olugboji
Department of Earth and Environmental Sciences, University of Rochester
Siyu Xue
Georgen Institute of Data Sciences, University of Rochester
Jean-Joel Legre
Department of Earth and Environmental Sciences, University of Rochester

Corresponding Author:[email protected]

Author Profile
Yuri Tamama
Seismological Laboratory, California Institute of Technology, Department of Geosciences, Princeton University, Department of Earth and Environmental Sciences, University of Rochester

Abstract

Africa’s continental crust hosts a variety of geologic terrains and is crucial for understanding the evolution of its longest-lived cratons. However, few of its seismic models are yet to incorporate the largest continent-wide noise dispersion datasets collected on the continent. Here, we report on new insights into Africa’s crustal architecture obtained using a new dataset and model assessment product, ADAMA, which comprises a large ensemble of short period surface wave dispersion measurements. We construct a continent-wide model of Africa’s Crust Evaluated with ADAMA’s Rayleigh Phase maps (ACE-ADAMA-RP). Phase and group dispersion maps are obtained with a probabilistic inverse modeling approach allowing us to provide constraints on uncertainty.  Error statistics suggest Rayleigh phase maps are better resolved and a perturbational inverse approach based on Rayleigh waves is the basis of our update of Africa’s crustal shear velocity. This model update reveals new insights into the architecture of Africa’s crust not previously imaged: (1) the fastest velocities confined to the edges of the Congo craton, the west-African cratons and the Sahara Metacraton, and (2) sharp spatial gradients along craton edges, mobile belts, and within rifted margins. While most of the reported features are robust, probabilistic modeling suggests caution in interpreting features where illumination is compromised by low-quality measurements, sparse coverage or both. Future extension of our approach to other complementary seismic and geophysical datasets - e.g, multimode earthquake dispersion, receiver functions, gravity and mineral physics, will enable continent-wide lithospheric modeling that extends resolution to the upper mantle.
14 Jun 2023Submitted to ESS Open Archive
16 Jun 2023Published in ESS Open Archive