Non-Double-Couple components in moment tensors of various types of seismicity and their relation to anisotropy and fluid flow

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The discussion on the existence, origin and physical interpretation of Non-Double-Couple (NDC) components in the seismic moment tensor of earthquakes is a long-standing and ongoing debate with increasing relevance. Due to recent progress achieved in data-acquisition technology as well as by improved inversion algorithms it is now possible to determine earthquake-source parameters with unprecedented precision and a thorough study of the nature of NDC components is a realistic research target. Here, we propose to systematically analyse recently acquired state of the art seismic recordings of different types of earthquakes with regard to NDC contents and their relation to seismic anisotropy and fluid flow. Our study focuses on the application of newly developed moment tensor inversion algorithms to 1. Aftershock activity following the 1999 Mw=7.4 and Mw=7.1 Izmit and Düzce, Turkey, earthquakes, 2. Volcano-related seismicity monitored at the submarine Mt. Kolumbo, Greece, 3. Fluid-injection induced seismicity at the KTB deep borehole, SE Germany and 4. Acoustic Emissions (microearthquakes) observed during rock-deformation experiments in the laboratory. With the here proposed research programme we attempt to argue on the role of NDC faulting in the four different types of earthquakes. Furthermore, we wish to bridge the gap between geophysical field studies (where boundary conditions are fixed but not known precisely) and laboratory experiments (where boundary conditions are well defined).