Exploring geodynamics at different depths with shear wave splitting

• Main Author: Grund, Michael
• Other Authors: Ritter, J.
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: KIT-Bibliothek, Karlsruhe 2019
• Subjects: shear wave splitting; seismic anisotropy; Fennoscandia; LLSVP; ScanArray; lowermost mantle; deformation; geodynamics; D"; Baltic Shield; ddc:530; Physics; info:eu-repo/classification/ddc/530; Fennoscandian
• Online Access: https://publikationen.bibliothek.kit.edu/1000091425; https://publikationen.bibliothek.kit.edu/1000091425/23788568; https://doi.org/10.5445/IR/1000091425; http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:swb:90-914257

Dynamic processes in the Earth's interior are the dominant driving forces behind the continuous deformation-related reworking of its surface. The characterization of deformation caused by past tectonic events near the Earth's surface as well as mapping of ongoing dynamic-driven processes deep inside the Earth are therefore major objectives to understand the dynamics of our planet. Seismic anisotropy, the direction-dependence of seismic wave speed, is directly related to deformation processes and can be "felt" by passing seismic waves. Although seismic anisotropy is a well-known phenomenon, the individual contributions from different depth ranges are still debated. However, recordings available from dense and large-aperture seismic station networks, provide the opportunity for resolving both, small-scale variations relatively close to the surface as well as so far unknown structures at greater depth. In 2012, an international seismological field experiment, called ScanArray, was initiated. The combination of 72 temporary broadband stations with long-running national permanent stations and arrays resulted in a recording network consisting of 266 seismic stations in total that were distributed across the Fennoscandian peninsula in northern Europe. Fennoscandia opens the opportunity to study the (past) geodynamical evolution of crustal and upper mantle structures far away from currently active plate tectonics. The main goal of this study is to characterize the anisotropic structure beneath the Fennoscandian peninsula as well as in the Earth's lowermost mantle based on a uniformly processed data set provided by the ScanArray network. For this purpose single-event shear wave splitting analysis was performed using core-refracted shear waves (SKS, SKKS, PKS) of around 3000 globally distributed teleseismic earthquakes (1998-2017). In order to improve the data coverage at a recording station, a new plugin (StackSplit) for a widely applied analysis software (SplitLab) is introduced allowing efficient and flexible handling ...