AF2019 is an azimuthally anisotropic S-wave tomographic model of Africa computed using waveform tomography. It is computed from a database of over 1.2 million vertical component waveform fits. It samples the crust and upper mantle including the mantle transition zone.
|Title||3-D shear-wave model for Africa from waveform inversion with a massive dataset|
|Type||Tomographic Earth model|
|Sub Type||Shear-wave velocity model|
|Data Revision||r0.0 (revision history)|
|Short Description||AF2019 is an azimuthally anisotropic S-wave tomographic model of Africa computed using waveform tomography. It is computed from a database of over 1.2 million vertical component waveform fits. It samples the crust and upper mantle including the mantle transition zone.|
|Authors:||Nicolas Luca Celli – Dublin Institute for Advanced Studies, Dublin, Ireland
Sergei Lebedev – Dublin Institute for Advanced Studies, Dublin, Ireland
Andrew J. Schaeffer – Geological Survey of Canada, Pacific Division, Sidney Subdivision, Natural Resources Canada, Sydney, BC, Canada
Carmen Gaina – Centre for Earth Evolution and Dynamics (CEED), University of Oslo, Oslo, Norway
|Reference Model||Our 3D reference model comprises CRUST2 for the crust, with added topography and bathymetry, and our own 1D average for the upper mantle. The model distribution netCDF is truncated to depths >56 km because of the irregular gridding of the crustal depths. To plot cross-sections at the crustal depths, please use the dedicated tool in the distributed model bundle (see the readme in it for instructions).|
|Model Download||AF2019.r0.0.nc (see metadata) is a pre-gridded model in netCDF 3 Classic format that includes the reference model.
AF2019_distribution.zip is the distribution model bundle (see the Reference Model section above
|Depth Coverage||The model samples depths from the crust to the bottom of the mantle transition zone (660). The best resolution is achieved at 56-410 km depth. While it samples the full transition zone, the model is underdamped in the lower transition zone (585-660 km depth), and there it should be used with extra care.|
|Area||The model spans between longitude -25°/63°, latitude -40°/40° and depth down to 660 km|
|Data Set Description||Our model is constrained by over 1.2 million seismograms. The global waveform dataset is from recordings at 6360 seismic stations, using 27550 earthquakes in total.|
|Model resolution||Our model is focussed on the Africa region, with the data coverage in this region maximized (all freely available broadband data were included) and the regularisation tuned to optimize the resolution in Africa. The global data complements the regional dataset and ensures dense sampling of entire Africa and its surroundings. Every model-grid node of the model is sampled by at least 7767 paths. The model is parametrized using a triangular grid with an average 327 km inter-knot spacing and with a depth parametrization over 18 and 10 triangular basis functions for S- and P-wave velocities, respectively (S- wave velocities: 7, 20, 36, 56, 80, 110, 150, 200, 260, 330, 410−, 410+, 485, 585, 660−, 660+, 809 and 1007 km; P-wave velocities: 7, 20, 36, 60, 90, 150, 240, 350, 485 and 585 km).|
To cite the original work behind this Earth model:
- Celli, N.L., Lebedev, S., Schaeffer, A.J. et al. African cratonic lithosphere carved by mantle plumes. Nat Commun 11, 92 (2020). https://doi.org/10.1038/s41467-019-13871-2
To cite IRIS DMC Data Products effort:
- Trabant, C., A. R. Hutko, M. Bahavar, R. Karstens, T. Ahern, and R. Aster (2012), Data Products at the IRIS DMC: Stepping Stones for Research and Other Applications, Seismological Research Letters, 83(5), 846–854, https://doi.org/10.1785/0220120032.
DOI for this EMC webpage: https://doi.org/10.17611/dp/emc.2022.af2019.1
- Bassin, C., Laske, G. & Masters, G. The Current Limits of Resolution for Surface Wave Tomography in North America. EOS Trans AGU 81, F897 (2000).
- Lebedev, S. & van der Hilst, R. D. Global upper-mantle tomography with the automated multimode inversion of surface and S-wave forms. Geophys. J. Int. 173, 505–518 (2008).
- r0.0 model provided by Nicolas Luca Celli
revision r0.0: uploaded October 20, 2022.