Paula Koelemeijer
Similar as on the Earth’s surface, intriguing landscapes are present deep inside our planet, reflecting the complex processes at work since its formation. To image these landscapes, surface recordings of seismic waves generated by earthquakes are combined using techniques similar to those in medical CT scanning. The tiny signals recorded at the Earth’s surface allow us to answer fundamental questions about its interior, such as: How has the Earth evolved to its present day state? Does the Earth’s mantle behave like a pan of boiling water, heated by the core and cooled at the surface, or more like a gigantic lava lamp, with large-scale compositional variations existing throughout? These questions are important as they inform us about dynamic processes within the Earth that are relevant for its habitability and help us to understand why the evolution of the Earth differs from other planets in our solar system.
In my research, I address these questions by using seismic observations to characterise the three-dimensional structures in the deep Earth, where we find continent-sized structures existing next to ponds of possibly molten material. I combine these with the results from geodynamical models and insights from mineral physics, with the aim to unravel the long-term evolution and inner workings of our planet.
Surface observations of the free oscillations of the Earth (“Earth’s music) allow us to image seismic structures deep below our feet. Here, we see the continent-sized structure characterised by low seismic velocities (“blob”) that is present underneath Africa.
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- Koelemeijer, P, Deuss, A & Ritsema, J 2017, 'Density structure of Earth's lowermost mantle from Stoneley mode splitting observations', Nature Communications, vol. 8, 15241, pp. 1-10. https://doi.org/10.1038/ncomms15241
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Koelemeijer, P, Ritsema, J, Deuss, A & van Heijst, HJ 2016, 'SP12RTS: a degree-12 model of shear- and compressional-wave velocity for Earth's mantle', Geophysical Journal International, vol. 204, no. 2, pp. 1024-1039. https://doi.org/10.1093/gji/ggv481
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Lecocq, T, Hicks, S, Van Noten, K, van Wijk, K, Koelemeijer, P, De Plaen, R, Massin, F, Hillers, G, Anthony, RE, Apoloner, M-T, Arroyo-Solórzano, M, Assink, JD, Büyükakpınar, P, Cannata, A, Cannavo, F, Carrasco, S, Caudron, C, Chaves, EJ, Cornwell, DG, Craig, D, den Ouden, OFC, Diaz, J, Donner, S, Evangelidis, CP, Evers, L, Fauville, B, Fernandez, GA, Giannopoulos, D, Gibbons, SJ, Girona, T, Grecu, B, Grunberg, M, Hetényi, G, Horleston, A, Inza, A, Irving, JCE, Jamalreyhani, M, Kafka, A, Koymans, MR, Labedz, CR, Larose, E, Lindsey, NJ, McKinnon, M, Megies, T, Miller, MS, Minarik, W, Moresi, L, Márquez-Ramírez, VH, Möllhoff, M, Nesbitt, IM, Niyogi, S, Ojeda, J, Oth, A, Proud, S, Pulli, J, Retailleau, L, Rintamäki, AE, Satriano, C, Savage, MK, Shani-Kadmiel, S, Sleeman, R, Sokos, E, Stammler, K, Stott, AE, Subedi, S, Sørensen, MB, Taira, T, Tapia, M, Turhan, F, van der Pluijm, B, Vanstone, M, Vergne, J, Vuorinen, TAT, Warren, T, Wassermann, J & Xiao, H 2020, 'Global quieting of high-frequency seismic noise due to COVID-19 pandemic lockdown measures', Science, vol. 369, no. 6509, pp. 1338-1343. https://doi.org/10.1126/science.abd2438