In Geodesy, the development of accurate Digital Elevation Models of the surface helps to provide height data for various applications in other Earth Science disciplines. These models are used as base models for studies. Geophysics can be a support science when providing base mode
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In Geodesy, the development of accurate Digital Elevation Models of the surface helps to provide height data for various applications in other Earth Science disciplines. These models are used as base models for studies. Geophysics can be a support science when providing base models for non-invasive studies inside the Earth. Such models can be multi-dimensional velocity models, where the relation of velocities and depth can be used for other structural parameter studies in e.g. Geodynamics or Geochemistry. With technological advancements in the recent decade, there is incentive to provide new regional continental-scale models. Full-waveform inversion (FWI) is an imaging method that iteratively inverts through seismic waveforms for structural heterogeneities in the Earth to create a high resolution static im- age. The development of event-specific adaptive SmoothieSEM meshes for regional meshes leads to a substantial decrease in computational costs of the FWI by lowering the amount of mesh elements needed to model a wavefield. This allows to push regional continental-scale tomographies towards period bands that were previously cost-prohibitive. Divided into two tomographic studies, on a bigger continental-scale mesh of Europe and Western Asia and a smaller mesh focused on Europe respectively, the study areas are lowered to a period of 24s. The reference base model is derived from the current generation of the Collaborative Seismic Earth Model (CSEM). Starting at a minimum period of 50s, the mimimum period is pushed in steps towards the target of 24s in a multiscale inversion approach to enable monotonic misfit reduction. The misfit optimization of the synthetic and observed waveforms is based on time-frequency phase misfits while the gradient optimization is based on the trust-region limited memory Broyden-Fletcher-Goldfarb-Shannon (L-BFGS) method and dynamic mini- batches. Waveform fits are quantified by the reduction of the time-frequency phase misfit and normalized amplitude difference misfits between the end model and the CSEM base model. The waveform inversion reveals more heteregeneous structures in Europe and Western Asia compared to previous studies.