Collaborative Research:AfricaArray - Imaging the African Superplume
The African Superplume is a large region of low seismic wave speeds in the lower mantle under southern Africa that has long been recognized as one of the most prominent features of the mantle. Above the African Superplume lies the African Superswell, suggesting a geodynamic link between lower mantle dynamics and geologic processes shaping the African plate. The origin and nature of the African Superplume is controversial. The initial interpretation of the low wave speed region under southern Africa attributed it to a long-lived, hot mantle upwelling. A number of seismic studies since then have suggested the presence of chemical heterogeneity within the superplume.
What parts of the superplume anomaly are thermal vs. chemical (or both) remains uncertain, as does its origin. In this project, the structure, composition and origin of the African Superplume will be investigated using the first 3 years of broadband seismic data from AfricaArray, together with existing data, and concentrating on four types of analyses; 1) tomographic imaging of the upper and lower mantle using body wave travel times, 2) modeling waveforms of teleseismic body wave phases that sample the Superplume, 3) jointly inverting receiver functions and surface wave dispersion measurements for crust and uppermost mantle structure, and 4) stacking and migrating receiver functions to image topography on the 410 and 660 km discontinuities.
AfricaArrayis a new 10-year-long Pan-African training and research initiative in geophysics, with an emphasis on seismology, set up by the University of the Witwatersrand, the Council for Geoscience (South African geological survey), and Penn State. AfricaArraywill provide the U.S. geophysics community with important seismic data on earth structure and processes for many years. AfricaArraywill greatly strengthen scientific ties between the U.S. geophysics community and earth scientists throughout Africa. Once established, AfricaArraywill provide opportunities for promoting geophysics to U.S. minority groups, as well as other students, through summer internships and a summer geophysics field course (both in Africa).
This award is co-funded by NSF's Office of International Science and Engineering.
