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Meeting of the Franco-Ecuadorian laboratory on Volcanoes and Earthquakes in Central Andes
This week, the final meeting of the Joint Laboratory between France and Ecuador (so-called LMI SVAN) was held in Quito. The LMI SVAN is supported by three French institutes (LMV: Laboratoire Magmas et Volcans, Clermont-Ferrand; Géosciences Azur, Sophia; ISTERRE, Grenoble) and the Escuela Politecnica Nacional - IG (Institute of Geophysics) from Ecuador. Several other institutes, including IRSN, also participate to investigations.The community gathered during three days of talks and discussions on earthquakes, tectonics, volcanism and related hazards in Ecuador. Many results were acquired during the last 4 years and talks were organized in 4 thematic sessions in the field of volcanology and 5 in seismology and active tectonics. The complete program is online @ http://lmi.igepn.edu.ec/quienes-somos/noticias/item/18-encuentro-del-lmi-svan-2016.The mascot of the Escuela Politecnica Nacional de Quito: "The weel-being of human-kind comes from science"This meeting, with a regional target and a wide thematic range, was a unique opportunity to exchange with associated researchers on specific geological objects and to go ahead in their understanding. Dealing with our (IRSN team and the rest of Active Tectonics team of the LMI SVAN) own theme on active tectonics and earthquake geology in Central Ecuador, we really enjoyed discussions with volcanologists who could perform big advances in deposit stratigraphy and dating: this is, for us, a huge progress in our fault mapping and characterization (faulting history, slip rate), because most of regional surface geology is made up with volcanic and volcano-sedimentary layers!During the Meeting, one of the most striking information is that the previously "old" volcanoes (Huisla, Igualata) disrupted by the Pallatanga Fault System (black arrows) are younger than 500 ky (comm. pers. Pablo Samaniego)!
A DEM view of the Riobamba-Ambato region, with its inactive (Igualata, Huisla, Carihuairazo, Chimborazo) and active (Tungurahua) volcanoes. The "oldest" are cut by the fault system (black arrows).There, I presented with my co-authors a compilation of our field work results, trying to provide some perspective for the future Fault-based PSHA calculation.Our conclusion slide, summarizing our interpretation of the fault segmentation in the Riobamba-Ambato regionOur preliminary interpretation of the fault mapping leads to a first scheme of possible segmentation in the central part of the CCPP fault zone which runs from the coast line (Guayaquil) to Colombia, bounding to the east the North Andean Sliver (Nocquet et al., 2014). This scheme will be refined in the next 4 years for sure, but our last reconnaissance field campaigns suggest that the continuous Pallatanga segment may be partly split in shorter segments when penetrating in the Inter-Andean Valley and the Cordillera Real. Part of deformation might be transferred to the North-South active folds which are a striking feature in the Salcedo-Latacunga landscape (see below).
A view at the Laguna Yambo, which is dammed by a growing fold (the elongated hill)This on-going work on fault segmentation will lead to crucial output for Seismic Hazard Assessment. Previously estimated without fault sources, we now will be able to model fault sources.