Collaborative Research: The interplay of surface evolution, shallow magmatism, a large hydrothermal system, and hazards at Puyehue-Cordon Caulle Volcanic Complex, Chile

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Volcanic landscapes pose a variety of natural hazards to local and regional communities, including volcanic explosions and outpouring of lava, large-scale land sliding of resulting steep terrains, and the formation of shallow hydrothermal systems. The hydrothermal systems affect water quality and weaken the overlying rocks further increasing the likelihood of major landslides. Larger volcanic eruptions may impact air traffic and therefore disrupt the global economy. Several of these geohazards occurred during the large 2011-12 eruption of Cordón Caulle, Chile, with its volcanic ash plume reaching large parts of South America including Buenos Aires. The natural hazards continue to pose a major risk for the region, because the eruption was accompanied by a shallow intrusion of magma that has established a vigorous hydrothermal system within a steep edifice scarred by numerous large surface cracks, indicative of slope instability. This eruption sequence, the near-surface intrusion, and its surroundings present a unique opportunity to advance our understanding of the genesis and current state of this recently formed intrusion, which serves as a model for near-surface magmatic intrusions globally. The goal of this project is ability to evaluate and understand the natural hazards associated with intrusions, in particular those arising from the interactions between surface processes, hydrothermal, and magmatic processes. Furthermore, the proposed work aims to advance our understanding of how volcanic eruptions transition from explosive to effusive behavior and these transitions may lead to the formation of shallow intrusions. In addition to building a strong US-Chilean collaborative effort with this project, the team will facilitate a large community-research component, where students will be invited to participate in field and other research activities.Subduction zones create volcanic arcs that are dynamic environments of steep terrain built and modified by the interplay between volcanic, plutonic, and landscape processes. Water acts as the key agent for dynamical interactions, in the form of the hydrothermal system that exists in the shallow subsurface and in the form of erosional processes. Understanding of how the magmatic-hydrothermal sphere and surface- and hydrosphere interact when volcanic activity fundamentally alters the landscape on decadal time scales remains a major challenge. The proposed project is centered around the 2011-12 Córdon Caulle laccolith, one of the most dynamic landscapes on Earth. It is unique because of the intersection of an active plutonic and volcanic realm with the shallow subsurface and surface. It affords the opportunity to study ongoing processes that act at the intersection of magma pathways to the surface, shallow magma intrusion, hydrosphere, and surface. The focus will be on enhancing knowledge about laccolith initiation and development through the integration of existing and newly proposed observations with geophysical and geochemical models, in order to ascertain the current state of the system and project its future evolution. The project combines methods of volcanology, geophysics, aqueous geochemistry, and geomorphology. It will add new insight into the internal and external processes that build and modify near-surface intrusions. It aims to answer why buoyant magma, despite having already an open path to the surface, intruded laterally within hundreds of meters of the surface. Beyond exploration of laccolith genesis, the project seeks to provide a basis for assessing its current state and future evolution through the integration of a wide range of existing and newly proposed observations of structure, mass and heat flux in and out of the intrusion, and its surface evolution as modulated by the interior and exterior processes. The project will foster international collaborations that strengthen scientific relationships between the US and Chile. The project will have an open structure that actively broadens the science community working on this volcanic system via a field school component. An outreach component will involve rural middle schools that are directly affected by regional volcanism. This project is jointly funded by Frontier Research in Earth Sciences (FRES) and the Established Program to Stimulate Competitive Research (EPSCoR).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.