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Investigating hazards and the evolution of volcanic landscapes by means of terrestrial and satellite remote sensing data and modelling


IPGP - Îlot Cuvier


Séminaires Tectonique et Mécanique de la Lithosphère

Salle 310

Nicole Richter


Volcanoes transform landscapes through complex and dynamic processes that vary on both spatial and temporal scales. We employ modern terrestrial and satellite-based techniques to study the changing morphologies of two fundamentally different volcanoes: Láscar, one of the most active andesitic subduction zone volcanoes of the North Chilean Andes, and Fogo, a basaltic ocean island volcano and the active expression of the Cabo Verde hotspot. With this work, we aim to advance both our fundamental understanding of the key processes that are controlling and driving eruptions and our ability to assess related volcanic hazards. While at Láscar geomorphological changes occur slowly and in confined areas, Fogo, in this work, exemplifies large-scale and rapid volcanic landscape transformation. At Láscar, we use high-resolution TerraSAR-X SpotLight interferometry to look at the small-scale 3D deformation field within the volcano’s summit craters between mid-2012 and early-2017. Results provide constraints on existing theories of long-term nested crater formation and evolution. Complexities of the retrieved signal suggest superposition of multiple formation mechanisms in addition to short-term processes. At Fogo, we use topographic data acquired before and after the 2014-2015 eruption to assess lava flow hazards associated with this, and the next, effusive crisis. We find that the lava flow hazard changed as a consequence of the changing topography; however, the probability of lava flow invasion remains high where two main villages within the caldera are being rebuilt. Results of this work highlight the advantages of integrating multiple techniques to study processes of volcanic landscape transformation on a variety of spatio-temporal scales. We highlight the importance of maintaining and further developing high-resolution SAR satellite modes and missions to study fundamental volcanic processes that may only manifest themselves as localized surface expressions, and we emphasize the necessity for systematic, repeated and detailed topographic mapping of volcanoes to aid hazard assessment.