Seismic anisotropy and attenuation retrieved from waveform recordings of acoustic emissions and observations of natural and induced seismicity

地震矩张量分析是地震地震学和岩石物理学中一个发展迅速的领域。因此，通常假定各向同性介质的性质。然而，地震观测证实，大多数岩石是各向异性的和衰减的。这些特性不仅影响波场的传播，还影响震源的特性。特别是，地震矩张量的反演比较复杂，而且不可能直接解释各向异性介质中的矩张量。该项目的主要目标是开发确定地质构造地震各向异性的新方法，并将这些方法应用于具有自然和诱发地震活动的地震活跃区，以完善地震力学模型，以改进震源区的特征。对于各向异性和粘弹性介质，应用一种新的矩张量反演方法可以得到高质量的矩张量和源张量。评估各向异性和衰减介质中的完整力矩和源张量将允许获得有关裂缝几何形状、裂缝过程和裂隙岩石性质的更详细信息。该项目的成果将发现与碳氢化合物和地热储集层的诱发地震活动有关的工业应用，以及关于火山和地震活跃地区增加的危险的详细知识。评估各向异性和衰减介质中的完整力矩张量将使我们能够获得关于裂缝几何形状、断裂过程和裂隙岩石性质的更详细的信息。

Analysis of seismic moment tensors is a rapidly developing field in earthquake seismology and rock physics. Hereby, isotropic medium properties are usually assumed. However, seismic observations confirm that most rocks are anisotropic and attenuating. These properties jointly affect the propagating wavefields but also properties of seismic sources. In particular, the inversion for the seismic moment tensors is more complicated and a straightforward interpretation of moment tensors in anisotropic media is not possible. The main objective of this project is to develop new methods for determining seismic anisotropy of geological structures and to apply these methods to seismically active regions with natural and induced seismicity in order to refine seismo-mechanical models towards an improved characterization of the focal zone. High quality moment and source tensors will be retrieved by applying a new method of moment tensor inversion for anisotropic and viscoelastic media. Evaluating the complete moment and source tensors in anisotropic and attenuating media will allow getting more detailed information on the geometry of fractures, the fracture processes and on the properties of the fractured rock. The results of the project will find industrial applications related to induced seismicity in hydrocarbon and geothermal reservoirs as well as detailed knowledge about increased hazard in volcanic and seismically active regions. Evaluating the complete moment tensors in anisotropic and attenuating media will allow us to get more detailed information on the geometry of fractures, the fracture processes and on the properties of fractured rock.