Long Period Magnetotellurics in Western Uganda

利用大地电磁法研究鲁文佐里山及其以东地壳和上地幔的电导率结构。在两次野外调查中，将在远震站点之后测量4条剖面（短周期，100公里/条剖面）。另外将安装10个长期站点（10-100000s）。这些测量将提供详细的三维图像，显示从上地壳到几百公里深处的上地幔的导电特征。将实现下列目标：a) Rwenzoris以东沉积物厚度的测绘，b)导电断层的几何形状和深度范围的研究，c)导电构造与孕震带的对比，d)电性各向异性与断层平面解的对比，e)包括各向异性在内的电性软流圈的测绘，f)利用岩石学结果研究电导率机制，特别是水的影响，g)约束地球动力学建模。深层地壳和上地幔结构的建模和解释将与远震组密切合作进行。地震资料和大地电磁学资料的互补性使我们能够区分关于裂陷韧性根的各种不同模型，并考虑到流变学、温度和岩石成分的影响。对观测资料的解释将成为今后3年（研究股第4-6年）进行更详细大地电磁调查的基础。

The conductivity structure of the crust and upper mantle beneath and east of the Rwenzori mountains will be investigated with the magnetotelluric method. During 2 field surveys altogether 4 profiles (short periods, 100 km/profil) will be measured following the teleseismic sites. Additionally 10 long period sites (10-100000s) will be installed. The measurements will give a detailed 3D image of conductive features from the upper crust down to several hundred kilometers into the upper mantle. The following goals will be pursued: a) Mapping of the thickness of the sediments east of the Rwenzoris, b) investigation of the geometry and depth range of conductive faults, c) correlation of conductive structures with the seismogenic zone, d) correlation of electrical anisotropy with fault plane solutions, e) mapping of the electrical asthenosphere including anisotropy, f) investigation of conductivity mechanisms, especially the influence of water, using petrologic results, g) constraining geodynamic modelling. The modelling and interpretation of structures in the deeper crust and upper mantle will be performed in close co-operation with the teleseismic group. The complementary nature of seismologic and MT data enables to distinguish between a variety of different models concerning the ductile roots of rifting and to take into account the effects of rheology, temperature and rock composition. The interpretation of the observations will form the basis for more detailed magnetotelluric investigations during the following 3 years (year 4-6 of the Research Unit).