Search for dissertations about: "Laust B. Pedersen"

Found 4 swedish dissertations containing the words Laust B. Pedersen.

2. 1. From 2D to 3D Models of Electrical Conductivity based upon Magnetotelluric Data : Experiences from two Case Studies

   Author : Juliane Hübert; Laust B Pedersen; Ari Tryggavson; Toivo Korja; Uppsala universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES;

   Abstract : Magnetotelluric measurements are among the few geophysical techniques capable of imaging the structure both in the shallow subsurface as well as the entire crust of the Earth. With recent technical and computational advances it has become possible to derive three-dimensional inversion models of the electrical conductivity from magnetotelluric data, thereby overcoming the problems arising from the simplified assumption of two-dimensionality in conventional two-dimensional modeling. READ MORE

4. 2. Improvement and Assessment of Two-Dimensional Resistivity Models Derived from Radiomagnetotelluric and Direct-Current Resistivity Data

   Author : Thomas Kalscheuer; Laust B. Pedersen; Christopher Juhlin; Roland Roberts; Heinrich Brasse; Uppsala universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Electromagnetic geophysics; radiomagnetotellurics; direct-current resistivity; displacement currents; dielectric effect; non-linearity; inversion; regularization; two-dimensional model; model variance; model resolution; data resolution; Geophysics; Geofysik;

   Abstract : Two-dimensional (2-D) models of electrical resistivity are improved by jointly inverting radiomagnetotelluric (RMT) and direct-current resistivity (DCR) data or by allowing for displacement currents in the inversion of RMT data collected on highly resistive bedrock. Uniqueness and stability of the 2-D models are assessed with a model variance and resolution analysis that allows for the non-linearity of the inverse problem. READ MORE

5. 3. Inversion and Joint Inversion of Electromagnetic and Potential Field Data

   Author : Jochen Kamm; Ari Tryggvason; Laust B Pedersen; Mehrdad Bastani; Douglas Oldenburg; Uppsala universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Inversion; Electromagnetic methods; Joint inversion; Potential Field methods; Inversion; Elektromagnetische Verfahren; Joint-Inversion; Potentialverfahren; Geofysik med inriktning mot fasta jordens fysik; Geophysics with specialization in Solid Earth Physics;

   Abstract : In this thesis, four inversion problems of different scale and difficulty are solved. Two of them are electromagnetic inverse problems. Two more are joint inversion problems of potential field data and other types of data. READ MORE

6. 4. Characterization of Hydrogeological Media Using Electromagnetic Geophysics

   Author : Niklas Linde; Laust B. Pedersen; Max A. Meju; Uppsala universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Geophysics; Hydrogeophysics; radio magnetotellurics; ground penetrating radar; electrical resistance tomography; inversion; regularization; geostatistics; electrical anisotropy; fractured rock; Geofysik; Geophysics; Geofysik;

   Abstract : Radio magnetotellurics (RMT), crosshole ground penetrating radar (GPR), and crosshole electrical resistance tomography (ERT) were applied in a range of hydrogeological applications where geophysical data could improve hydrogeological characterization. A profile of RMT data collected over highly resistive granite was used to map subhorizontal fracture zones below 300m depth, as well as a steeply dipping fracture zone, which was also observed on a coinciding seismic reflection profile. READ MORE