Imaging Induced Seismicity at the KTB

通过地震台网观测自然或人工产生的声发射（即小地震）是成像地球传输过程的有力工具。在KTB的注射实验中，观察到大量的事件。地震事件的精确时空特征是至关重要的，因为所有以下解释（例如，输运性质）完全依赖于这个结果。事件的本地化取决于用于本地化的模型。KTB岩石的各向异性是众所周知的特征，但在局部化中没有考虑到。先前的研究表明，这导致了事件定位的严重错误。在这项研究中，我们将首先利用P波和s波的三维各向异性断层成像技术，从综合KTB VSP数据集确定各向异性弹性特征。这一步对于本地化是必不可少的。获得的层析各向异性三维模型将用于2000年和2004年注入实验的声发射定位。一项新开发的基于反向建模或时间反向声学镜的技术将用于对事件进行成像。这种技术不需要挑选事件，由于该方法的叠加特性，提高了网络的检测水平，并允许定位在网络的单个地震图中不可见的到达点。

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.