AfricaArray: Imaging the African Superplume

1. AfricaArray: Imaging the African Superplume Andy Nyblade,Dept. of Geosciences, Penn State University, University Park, PA Paul Dirks, School of Geosciences, University of the Witwatersrand, Johannesburg, South Africa Iris Workshop, Tucson June 10, 2006 www.africaarray.psu.edu

2. AfricaArray - A public-private partnership supporting capacity building for Africa’s natural resource sector • to support in-situ training and research programs to help build a scientific workforce --initially in geophysics • As part of the training and research programs, create a network of shared scientific observatories (initially broadband seismic stations) to promote education, research, and community building “AfricaArray” = array of training programs + array of research projects + array of partnerships and collaborations+ array of scientific observatories

3. AfricaArray - a fortuitous convergence of many things • Science - clear need for improved data coverage in Africa • Education - clear need for improved geophysics training in Africa--extractive industries are booming • Community support - in Africa, US and Europe • Funding opportunities - private (industry) and public (gov’t)

4. The African Superplume • (The African Anomaly) • Largest seismic anomaly • in the mantle • Structure best resolved in • the lower mantle • Thermal and compositional • anomaly -- several lines • of reasoning • Structure poorly resolved • at mid-mantle depths

5. The African Superswell Anomalous elevation and bathymetry (Nyblade and Robinson, 1994)

6. Grand, 2002 Ritsema and Allen, 2003 Grand et al., 2002 Afar Afar

7. Passcal Experiments in Eastern Africa • Body wave travel time tomography • P and S waves • VanDecar’s method for inversion • Good azimuth distribution of events • 410 and 660 km discontinuity structure • stacking receiver functions

8. Ethiopia Benoit et al., Geology 2006

9. Afar West. Pl. MER West. Pl. MER West. Pl.

10. A’ A

11. Kenya B B’ Park and Nyblade GRL, (2006)

12. Tanzania Ritsema et al. (1998) a a’ a a’ Owens et al. (2000)

13. MER

14. SEPARATE THERMAL PLUME(S) VS SUPERPLUME • Observations that do not • favor plume head models: • Depth extent (>400-600 km) • of LVZ • Westward dip of LVZs along • Eastern Branch of rift system Griffiths and Campbell, 1990

15. Grand, 2002 Ritsema and Allen, 2003 Grand et al., 2002 Afar Afar

16. AfricaArray - Imaging the African Superplume AfricaArray Backbone Network • 18 BB stations 6/06 • 25-35 BB stations by 12/07

17. Itezhi-Tezhi, Zambia • Installed Jan. 2006 • Guralp 3T sensor • RefTek DAS • Mozambique Earthquake • 22 February, 2006 • Mw 7.0 TEZI, Zambia Vertical ground displacement

18. AfricaArray -- Imaging the African Superplume • AfricaArray experiments • filling in critical gaps in data coverage

19. Implementation (3 phases over 10 years) Phase 1 (years 1-3, started Jan. 2005) • improve and expand the geophysics program at the University of the Witwatersrand, South Africa • Broadband seismic stations installed or upgraded in participating countries as part of a permanent “backbone” seismic network (southern and eastern Africa) • temporary networks of seismic stations installed for focused projects • data from the seismic stations used for student research • data archiving at the IRIS DMC

20. Implementation Phase 2 (years 4-6) & Phase 3 (years 7-10) • support centers of excellence in geophysics regionally at other African universities (initiated already in Angola and Ethiopia) • develop research programs in other areas of geophysics: reflection seismology/basin analysis, potential fields, hydrogeophysics • expand network of permanent observatories and add other sensors (GPS, meteorological, hydrologic, other environmental sensors)

21. Progress so far • Education program • 2005: 10 BSc honors students (4th yr), 2 PhD students • 2006: 13 BSc honors students, 4 MSc, 4 PhD, 5 Postdocs • Backbone network of observatories • 18 operational seismic stations in 6 countries • 6 additional stations by end 2006 • Temporary seismic deployments • 2007-2010 Uganda and Tanzania (40 stations)

22. Progress so far • Science projects --General Theme “4D Imaging of the African Crust and Mantle” • African Superplume • Bushveld Complex • Congo Craton • E. African rift basins • Wits basin

23. Partnerships • Founding partners (provided in-kind support): • School of Geosciences, University of the Witwatersrand • Council for Geoscience (S. African Geol. Survey) • Penn State University • IRIS • Other partners • Government organizations in Africa, U.S., Europe • Many universities in Africa, U.S., Europe • Many geological surveys in Africa growing quickly!

24. Funding Partners • In-kind support ($2M) • Wits, CGS, PSU, IRIS • New funding raised • Gov’t: NSF, NRF, DOE, Belgium gov’t • Private: ExxonMobil, Schlumberger, De Beers, Total, Mineral Education Trust Fund (S. Africa), London Bullion Market, BHP Billiton • Exceeded target of $3M to start AfricaArray

25. More AfricaArray Activities….. • See poster • Go to our web site: www.africaarray.psu.edu • 1st AfricaArray workshop, July 13-14, University of the Witwatersrand, Johannesburg, South Africa