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Browsing by Author "Rodrigues, Isabel Novais Jasmins"

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  • Estabelecimento de cenários sísmicos para a região do Algarve com base em metodologias probabilísticas
    Publication . Rodrigues, Isabel Novais Jasmins; Sousa, Maria Luísa; Costa, Paula Teves, 1954-
    The main objective of this study is to establish seismic scenarios for the Algarve region, based on the disaggregation of its probabilistic seismic hazard. It is therefore expected to contribute to the reassessment of this region’s probabilistic seismic hazard in the framework of the collaborative research project Study of the Seismic and Tsunami Risks of Algarve (ERSTA, Estudo do Risco Sísmico e de Tsunamis do Algarve). This work begins by presenting ERSTA’s developments of hazard analysis models and input data that are the first steps to establish the seismic scenarios. Special focus is given to the completeness of seismic catalogue and to the estimation of the Gutenberg-Richter parameters. Subsequently, Seismic Hazard was disaggregated considering different spaces of random variables for peak ground acceleration (PGA) and for the 5%-damped 0.4 and 1.0 sec spectral acceleration levels of three return periods: 95, 475 and 975 years. Hazard disaggregation was analysed taking into account univariate conditional hazard distributions of M (magnitude), bivariate conditional hazard distributions of X-Y (seismic source’s latitude and longitude) and multivariate 4D conditional hazard distributions of M-(X-Y)-ε. Finally, modal values obtained from the 4D-disaggregation were identified as seismic scenarios for the Algarve’s 84 parishes.Seismic scenarios share a small number of geographical locations for all return periods and generally share the same pattern of increasing magnitude and distance with decreasing spectral acceleration periods. Finally, seismic hazard of most Algarve’s parishes is dominated by the seismicity located offshore, on the West of the region, in the seismogenic zone where the 1755 earthquake was generated. One may conclude that disaggregation analysis provides further insights into the sources that dominate the hazard at a given ground-motion level.
    2009Master thesis Restricted access Show more