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Abstract

The interior of the Earth is the least accessible region in our environment. Elastic waves, generated by large earthquakes, are used to explore the interior of the Earth. The globally recorded seismic signals must be inverted with mathematical techniques into models of the Earth. The reflectivity method, developed about fifty years ago for a one dimensional Earth model, is still one of the most successful techniques for modeling waveforms. The big advantage of this method is that it provides the complete response of the medium. It is not uncommon that new seismic signals are first discovered in theoretical seismograms before they are found in the observed data. Global seismology is primarily an observational science. It was founded by Ernst von Rebeur-Paschwitz in 1889 with the announcement in the journal “Nature” of the successful recording at the Royal Prussian Observatories in Potsdam of an earthquake that occurred in Japan. The installation of seismic stations and collection of data is still the primary task in Seismology. The GFZ German Research Centre for Geosciences and other international institutions are installing increasing numbers of seismic stations primarily for monitoring the global seismicity but also to study the dynamics of the Earth’s interior. With the increasing amount of data, it becomes clear that three dimensional models of the Earth’s interior are required to fit the data and that we might have a chance to identify the ongoing dynamics of the Earth in much greater detail. This requires new mathematical modeling and wave form inversion techniques for three dimensional Earth models, which are now the frontiers of computational seismology.