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Seismic tomography is an imaging tool which allows to construct 3-D models of the Earth’s internal structure from observables of seismic waves. Surface wave tomography can be performed using earthquakes and ambient noise data and is sensitive to isotropic as well as anisotropic 3-D shear-wave velocity structure in broad depth ranges sampling the crust and the lithosphere-asthenosphere structure. In this study, surface wave tomography is performed to characterize the structure of the lithosphere-asthenosphere underneath the Mediterranean and the adjacent regions. We utilize a large database consists of 3800 teleseismic earthquakes recorded by 4500 broadband stations provided by IRIS and EIDA in a combination, for the first time, with waveform data from the Egyptian National Seismological Network (ENSN). An automated algorithm for inter-station phase velocities is applied to obtain fundamental mode phase velocities from this database (3.5 millions of waveforms). Path average dispersion curves are obtained by averaging the smooth parts of single-event dispersion curves. We calculated new high resolution Rayleigh and Love wave phase velocity maps using an unprecedentedly large number (200.000) of measurements in the period range from 8s-350s. In order to relate the local dispersion curves to 1-D velocity models as function of depth, the Particle Swarm Optimization (PSO) algorithm has been developed and implemented. The 3-D model has been constructed based on the obtained 1-D shear velocity model.

Besides political and striking uncertainty, induced seismicity is a fundamental risk to the success of geothermal projects. The geothermal reservoirs Landau and Insheim are located on the western rim of the Upper Rhine Graben where the highest fluid temperatures in Germany provide a good foundation for geothermal energy production while the complex tectonic structure provides a difficult set-up for geophysical investigations. In this thesis I advance automatic processing algorithms and apply them to assess characteristics of induced seismicity at the two geothermal reservoirs. Key objectives are to complete existing detection catalogs, determine the reliability of automatic processing results and to identify characteristics of induced earthquakes at the geothermal reservoirs which in future may be linked to operational parameters of the power plants. Challenging the completeness of existing catalogs a complementary offline similarity detection approach which considers multiple master events per reservoir is proposed. The second algorithm is an autoregressive prediction (AR)-Akaike Information Criterion (AIC)-cost-function arrival time determination approach which is straightforward trainable for different datasets on different scales and able to reliably pick robust seismic P- and S-phase arrival times on single- and multi-component data. The resulting hypocenter offsets standard deviations are approximately 1 km horizontally as well as vertically. Finally from hypocenter relative relocations, I am able to identify a spatial separation of the Insheim earthquake clusters retrieved by the similarity detection algorithm. Two orientations of seismicity are found to coincide with the stress regimes, firstly a south-east to north-west orientation during graben activity, and secondly a rather south-to-north orientation of the recently more dominant stress regime from Alpine denudation.

We automated the inter-station method. The method automatically selects smooth parts of phase velocity dispersion curves for all the events in one inter-station path, an average dispersion curve is obtained for each inter-station path after statistical analysis of individual measurements. We applied the method to a huge data-set covering almost entire Europe and obtained phase velocity measurements in broad period range from 8s to more than 250 s for both Love and Rayleigh waves. We used phase velocity measurements in tomographic inversion and obtained high quality very broad band phase velocity maps for central and northern Europe. Synthetic reconstruction tests reveal that the regions with dense path coverage possess a lateral resolution of about 100 km to 150 km. The low period phase velocity maps clearly image the central European basin system (CEBS). At intermediate periods (e.g. around 60 s) Trans - European Suture zone marks a clear and distinct boundary between old and cold East European Craton with that of younger Phanerozoic central Europe. The boundary is sharp beneath the TTZ (Tornquist- Teisseyre Zone) on the south-estern part of the TESZ, where as gradual transition towards the north western part of the TESZ i.e. STZ (Sorgenfrei-Tornquist Zone). European slab is imaged clearly at western Alps and is visible at the periods from 40s to 120s.