Sökning: "Geophysics"
Visar resultat 16 - 20 av 210 avhandlingar innehållade ordet Geophysics.
16. 3D Geophysical and Geological Modeling in the Skellefte District: Implications for Targeting Ore Deposits
Sammanfattning : With the advancements in acquisition and processing of seismic reflection data recorded over crystalline rocks, building three-dimensional geologic models becomes increasingly favorable. Because of little available petrophysical data, interpretations of seismic reflection data in hardrock terrains are often speculative. LÄS MER
17. Statistical Seismology Studies in Central America : b-value, seismic hazard and seismic quiescence
Sammanfattning : The present thesis collects results of research applying theory and methods of statistical seismology to the seismicity of Central America, a region with a complex tectonic setting controlled by the interaction of four major plates, namely the Caribbean, Cocos, Nazca and North American plates.Three different earthquake catalogues were used for studies focused on stress in a tectonic volume, seismic hazard maps and seismicity patterns (precursors), covering the region 94ºW to 81ºW and 5ºN to 20ºN. LÄS MER
18. Analyses of Seismic Wave Conversion in the Crust and Upper Mantle beneath the Baltic Shield
Sammanfattning : Teleseismic data recorded by broad-band seismic stations in the Swedish National Seismic Network (SNSN) have been used in a suite of studies of seismic wave conversion in order to assess the structure of the crust and upper mantle beneath the Baltic Shield. Signals of seismic waves converted between P and S at seismic discontinuities within the Earth carry information on the velocity contrast at the converting interface, on the depth of conversion and on P and S velocities above this depth. LÄS MER
19. A Broad View on the Interpretation of Electromagnetic Data (VLF, RMT, MT, CSTMT)
Sammanfattning : The resolution power of single Very Low Frequency (VLF) data and multi-frequency Radiomagnetotelluric (RMT) data in delineating conductive structures typical for the sedimentary cover and crystalline basement in Scandinavia is studied with a view to future developments of the technique to increasing the frequency range into the LW radio band. Airborne and ground VLF data are interpreted and correlated with RMT measurements made on the ground to better understand the resolution power of VLF data. LÄS MER
20. Integrated geophysical-geochemical methods for archaeological prospecting
Sammanfattning : A great number of field measurements with different methods and instruments were conducted in attempts to develop a method for an optimal combination of various geochemical and geophysical methods in archaeological prospecting. The research presented in this thesis focuses on a study of how different anthropogenic changes in the ground can be detected by geochemical and geophysical mapping and how the results can be presented. LÄS MER