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Recent sedimentation on northern Venezuela continental margin (central coastal district) : imbricated record of climatic instabilities and earthquakes effects (landslides, tsunamis).

Abstract : The northern border of Venezuela (southern border of the Caribbean Plate) corresponds essentially to a relay of large active strike-slip faults, generating a steep and rugged margin (South of the Caribbean Sea, Pit and Gulf of Cariaco, Fig. 1). This region is therefore exposed to three sources of natural hazards: 1) earthquakes and direct effects, 2) tsunamis (related to these faults, to the more distant activity of the West Indies bows, or to submarine landslides), 3) slips and airflows, sometimes linked to sudden climatic events (see Vargas flash flood, December 1999). The second and third types of phenomena directly affect sedimentation, whether marine (littoral and platform), lagoon or lacustrine. In addition, the latest global (fast) changes in the sea level have subdivided and structured the sedimentary stack.The recent part of these deposits (about 150 000 to 200 000 years ago) was the subject of two preliminary high resolution seismic imaging campaigns, the first devoted to the eastern part (Gulf of Cariaco, Audemard et al. 2007, Van Daele et al., 2010) and the second at the central coast (between Cabo Codera and the Sad Gulf, Fig. 2). This second mission will be complemented by a new imaging acquisition and the taking of short cores at sea and in coastal lagoons. The interpretation of the seismic sections and the sedimentological analysis of the cores will be used for this work of thesis with a double aim: 1) to reconstruct the general evolution of the sedimentation on the margin, and the influence of the global environmental changes, 2) to know the geographical distribution and over time (for a period of at least 100,000 years) major catastrophic phenomena (earthquakes, tsunamis, flash floods) that have interbedded in this sedimentation. The possible impact of the superposition of external and seismo-tectonic phenomena (see the recent Tucacas earthquakes during a rainy episode) and the location of tsunami risk areas will be modeled and discussed.
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Sirel Colón. Recent sedimentation on northern Venezuela continental margin (central coastal district) : imbricated record of climatic instabilities and earthquakes effects (landslides, tsunamis).. Earth Sciences. Université Grenoble Alpes, 2018. English. ⟨NNT : 2018GREAU019⟩. ⟨tel-01884788⟩

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