Location of Seismic Events with the Diffraction-summation Method

The project CLEAN is a scientific program within the frame of an EGR (enhanced gas recovery) project in the Altmark natural gasfield (Sachsen-Anhalt) where the injection of 100000 t CO2 during the project shall enhance the gas production. The resulting effects will be investigated with the help of e.g. active and passive seismic measurements. The location of potential induced seismic events during such a project is important for different reasons, e.g. on one hand for the identification of pre-existent faults and to detect potential leakages (Rudledge, 2009), on the other hand to differentiate between induced and natural seismicity. The manual location of such events itself represents a great challenge, due to their potentially large number and low magnitude. In the frame of the project CLEAN a semi-automatic location procedure based on the diffraction-summation method shall be developed to enable the location of a large number of low-magnitude seismic events almost automatically and in real-time without picking. First the method was successfully tested on synthetic datasets. In a further step, the method was applied to mining induced events, where the location results were compared with the results of standard locations.