Investigation of the influence of mantle structures on Earth's core observations

• Applicant: Professorin Dr. Christine Thomas
• Subject Area: Geophysics
• Term: since 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 365859872

Seismic investigations of the Earth's core are often carried out using body waves and the waves PKP and SKS are of great importance here. Usually the assumption is made that the paths of the waves are similar in the mantle and that mantle structures can be neglected when analysing core phases. However, his assumption does not have to be correct and the aim of this proposal is to quantify how mantle structures can influence seismic core phases. For this we are planning to use array seismological methods for five paths and measure path deviations (slowness and backazimuth) of the seismic waves, which ultimately lead to travel time deviations. If the path deviations are neglected, the resulting travel time differences will be projected into the core and this can lead to mis-leading models if the inner core. The use of converted waves (SKP and PKS), which have a different path on part of the mantle path, in combination with PKP waves allow the differential investigation of mantle and core structures. In addition to the array observations, seismic 3D modeling will show the extent to which the paths and travel times of the seismic waves are influenced by high-resolution seismic velocity models (tomography) and which structures in the mantle and core generate path and travel time deviations those waves used in our study. Furthermore, using 3D modeling we aim to make predictions for different paths that can be used for future core investigations. The results of this study have an influence not only on seismological models but also on geodynamic and mineralogical investigations, since travel time variations have been used to constrain core anisotropy. By using PKP and SKS waves, which pass through the same regions in the mantle, structures of the lowermost mantle can also be better quantified, since the different effect of structures on S-waves and P-waves can provide information about deep Earth mineralogy.

• DFG Programme: Research Grants