Imaging Induced Seismicity at the KTB

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The observation of naturally or artificially generated acoustic emissions (i.e., small earthquakes) by seismic networks is a powerful tool to image transport processes in the earth. During the injection experiments at the KTB a large number of events were observed. The precise spatio-temporal characterization of the seismic events is of utmost importance since all following interpretations (e.g., transport properties) rely entirely on this result. The localization of the events depends on the model used for the localization. The anisotropy of the KTB rocks is a well known feature but was not considered for the localization. Previous studies demonstrate that this leads to severe errors in the location of events. In this study we will first determine the anisotropic elastic features from the comprehensive KTB VSP data sets using 3-D anisotropic tomography for P- and S-waves. This step is essential for the localization. The obtained tomographic anisotropic 3-D model will then be used for the localization of the acoustic emissions of the 2000 and 2004 injection experiments. A newly developed technology based on reversed modelling or time reversed acoustic mirrors will be used to image the events. This techniques does not require picking of events and increases the detection level of the network owing to the stacking character of the method and allows to locate arrivals not visible in the individual seismograms of the network.