Sökning: "Roland Roberts"

Visar resultat 6 - 10 av 16 avhandlingar innehållade orden Roland Roberts.

  1. 6. Investigating Time-Varying Processes Using Seismicity and Time-Dependent Tomography

    Författare :Alex Hobé; Ari Tryggvason; Olafur Gudmundsson; Roland Roberts; Nicholas Rawlinson; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Time-Dependent Tomography; Joint Inversion; Geothermal Energy; Volcanotectonics; Seismic Unrest; Fagradalsfjall Eruption; Geofysik med inriktning mot seismologi; Geophysics with specialization in Seismology;

    Sammanfattning : Our global society is affected by, and makes use of, many time-varying processes. Processes related to geothermal energy and CO2 sequestration can help mitigate climate change and reduce the number of premature deaths (millions annually) due to air pollution from fossil fuels. LÄS MER

  3. 7. Studies of Unusual Seismicity and Long Period Events at the Glacier Overlain Katla Volcano, Iceland

    Författare :Kristín Jónsdóttir; Roland Roberts; Björn Lund; Göran Ekström; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Geophysics; Geofysik; Geophysics Specialized In Seismology; geofysik; med inriktning mot seismologi;

    Sammanfattning : Earthquake catalogues are usually dominated by diffusive behaviour consistent with the Omori law of aftershocks. This is investigated in terms of waiting times, i.e. the time between successive events in a time-sorted earthquake catalogue. LÄS MER

  4. 8. Bias-adjusted analysis of global natural disaster records and an assessment of seismic hazard in Sweden

    Författare :Niranjan Joshi; Roland Roberts; Ari Tryggvason; Björn Lund; Kuvvet Atakan; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Power-law; Natural-disasters; Seismic-hazard assessment.;

    Sammanfattning : Natural disasters pose significant challenges today and demand efficient allocation of society’s limited resources for disaster risk reduction. This relies on analysis of natural disaster records, which are prone to (reporting) biases that can affect the inferences drawn from their analysis. LÄS MER

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

    Författare :Thomas Kalscheuer; Laust B. Pedersen; Christopher Juhlin; Roland Roberts; Heinrich Brasse; Uppsala universitet; []
    Nyckelord :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;

    Sammanfattning : 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. LÄS MER

  7. 10. Location and Relocation of Seismic Sources

    Författare :Ka Lok Li; Ólafur Gudmundsson; Roland Roberts; Ari Tryggvason; Lars Ottemöller; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Earthquake location; Earthquake relocation; Tremor location; Bayesian inversion; Correlation; Earthquake catalog; Iceland; Seismicity; Interferometry; Inverse theory; Volcanic tremor; Geofysik med inriktning mot seismologi; Geophysics with specialization in Seismology;

    Sammanfattning : This dissertation is a comprehensive summary of four papers on the development and application of new strategies for locating tremor and relocating events in earthquake catalogs.In the first paper, two new strategies for relocating events in a catalog are introduced. LÄS MER