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Percorrer por autor "Marques, Rui"

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  • Fault-mediated magma propagation and triggered seismicity revealed by the 2022 São Jorge Azores unrest
    Publication . Hicks, Stephen P.; Gonzalez, Pablo J.; Lomax, Anthony; Ferreira, Ana M. G.; Ramalho, Ricardo S.; Mitchell, Neil C.; Silveira, Graça; Dias, Nuno Afonso; Fontiela, João; Fernandes, Rui; Custódio, Susana; Tsekhmistrenko, Maria; Mendes, Virgílio; Pimentel, Adriano; Silva, Rita; Prates, Gonçalo; Sturgeon, William; Marignier, Augustin; Carrilho, Fernando; Marques, Rui; Miranda, Miguel; Garcia, Arturo M.
    Abstract Understanding failed volcanic eruptions is key to mapping magma plumbing and forecasting hazards. Faults and fractures guide magma, but their mechanisms remain unclear due to the lack of precise earthquake locations andlimited3-Dfaultmappinginvolcanicregions.The triple-junction setting of the Azores Archipelago, where volcanic systems and seismogenic faults coexist, offers a natural laboratory to study fault–magma interactions. We analysed ~18,000 earthquakes relocated to high precision using onshore and ocean-bottom seismometers, combined with geodetic data and seismic autocorrelation imaging, during a failed 2022 eruption on São Jorge Island. A magmatic dike ascended rapidly and mostly aseismically from the upper mantle, intruding a crustal fault before stalling ~1,600 m below the surface. Seismicity indicates that magma branching and lateral fluid escape along the fault triggered an intense, months-long swarm with rotated focal mechanisms. This study demonstrates the dual role of faults in facilitating and arresting magma ascent.
    2026-04-23Artigo de investigação Acesso aberto Ver mais
  • Seismic vulnerability and risk analysis of the old building stock at urban scale: application to a neighbourhood in Lisbon
    Publication . Lamego, Paula; Lourenco, Paulo B.; Sousa, Maria L.; Marques, Rui
    The old buildings represent an important fraction of the urban fabric of the cities, which have implicit societal issues, like safety. This work deals with the seismic vulnerability assessment and risk analysis of the old building stock, with application to a neighbourhood in Lisbon. The studied neighbourhood includes three frequent building typologies in Portugal, i.e. stone masonry, "Placa" and RC buildings. Reference buildings for each typology were numerically modelled using the equivalent frame method. Pushover analysis was then performed to derive the vulnerability characteristics of the reference buildings and more general building classes, i.e. capacity and fragility curves, in order to assess the seismic vulnerability of the buildings and perform a seismic risk analysis. This last analysis was performed to estimate the building damages and the economic and life losses for different earthquake scenarios. Most of the studied buildings are found to be unsafe to the considered seismic actions and will suffer severe damages with associated large losses.
    2017-07Artigo científico Acesso restrito Ver mais