Estimating mantle viscosity near the Hess rise from integrated electrical resistivity, seismic and geodynamic simulations

• Applicant: Professor Dr. Max Moorkamp
• Subject Area: Geophysics
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 568450807

The viscosity of the Earth's mantle significantly influences geodynamic processes such as plate movements and the large-scale topography of the Earth's surface. Despite decades of research, considerable uncertainties remain in viscosity estimates of the upper mantle, differing by one to two orders of magnitude. This project employs a novel geophysical approach to more precisely measure this fundamental parameter. The central idea is that the interaction between a plume and the overlying moving plate strongly depends on the viscosity contrast between the lithosphere and asthenosphere. In particular, the temporal evolution of plume material motion and the associated temperature anomaly is controlled by the viscosity profile of the asthenosphere. A high viscosity, for example, leads to strong coupling with the plate, transporting the plume material further in the direction of plate motion. To investigate this mechanism, we conduct large-scale electromagnetic and seismological measurements in the Hawaii-Emperor chain within a Japanese-German collaboration, using the Japanese RV Hakuhamura for instrument deployment and the German RV Sonne for instrument recovery. The investigation area, northwest of the currently active volcanic center, allows us to determine the location and extent of the present temperature anomaly resulting from past plume interactions. Using geodynamic simulations, we can infer the viscosity contrast between the lithosphere and asthenosphere from this geophysical data. This innovative geophysical approach offers a new way to estimate viscosity and helps resolve long-standing discrepancies between established methods. More accurate viscosity estimates will, in turn, improve our understanding of the processes governing the evolution of Earth's surface.

• DFG Programme: Research Grants
• International Connection: Japan
• Co-Investigator: Dr. Marion Jegen-Kulcsar
• Cooperation Partners: Dr. Kiyoshi Baba; Dr. Takehi Isse