Heterogeneities, Anisotropy and Attenuation in the Deep Earth through Seismic waveform studies (HAADES)

• Applicant: Dr. Stephanie Durand
• Subject Area: Geophysics
• Term: from 2015 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 289920201

This project aims at understanding the causes for seismic structures in the lowermost mantle, the D" region, by using a novel combination of seismic observables and modelling. Combining differential attenuation measurements, anisotropy and velocity observables of phases sensitive to the lowermost mantle with 2D/3D modelling will provide a better constraint on the lowermost mantle mineralogy and dynamics. The region is difficult to access due to its large depth and the only way to reach such a deep region is through the use of seismic waves. The long wavelength structure of the lowermost mantle is fairly consistently constrained but during the last two decades shorter length scale features have been overprinted so that the structure of the D" region has become more complex and more intriguing. These smaller-scale features have been reported through regional studies that did not systematically investigate the same seismic parameters and often combinations of observables has not been attempted. A global map of the D" structure is thus still unavailable that would help to understand the origin of its seismic structure. That is why we propose in this project to perform measurements of various D" seismic properties (anisotropy, attenuation, seismic velocities and reflectors) on a global dataset with internally consistent techniques that will be taken together in a joint interpretation. The proposed project will improve our knowledge of the seismic anomalies within the D" region which is crucial to constrain the dynamics and mineralogy of the Earth. Our approach of combining differential attenuation, anisotropy and reflector depths/velocities is unique and the results are expected to have an important impact on a wide variety of disciplines: it will contribute to answer geodynamical questions such as material exchange across the Core-Mantle Boundary (CMB) and heat budget of the Earth and it will also constrain the lower mantle mineralogy.

• DFG Programme: Research Grants
• Co-Investigator: Professorin Dr. Christine Thomas