A decade (2007-2017) of InSAR geodesy at Cordon Caulle volcano: a silicic eruptive cycle and evolution of a crystal mush observed from space

Monday, 8 January 2018
Salon Maule (Hotel Quinamavida)
Francisco Delgado, Cornell University, Ithaca, NY, United States, Jennifer Jay, National Museum of Natural History, Washington, DC, United States, Julia Kubanek, McGill University, Earth and Planetary Sciences, Montreal, QC, Canada, Matthew E Pritchard, Cornell University, Earth and Atmospheric Sciences, Ithaca, NY, United States, Kyle R Anderson, USGS Volcano Science Center Menlo Park, Menlo Park, CA, United States, Paul Lundgren, Jet Propulsion Laboratory, Pasadena, CA, United States, Daniel Basualto, OVDAS, SERNAGEOMIN, Temuco, Chile, Loreto Cordova, Observatorio Volcanológico de los Andes del Sur (OVDAS), Servicio Nacional de Geología y Minería (SERNAGEOMIN), Temuco, Chile and Luis Lara, SERNAGEOMIN National Geology and Mining Service, Santiago, Chile
Abstract:
The 2011-2012 eruption of Cordón Caulle volcano in Chile is the best scientifically observed rhyodacitic eruption and is thus a key place to understand the dynamics of these rare but powerful explosive eruptions. Using multiplatform InSAR data between 2007 and 2017, we document multiple episodes of metric-scale ground deformation that are directly related to the dynamics of the underlying plumbing system.


Pre-eruptive data show ~0.5 m of ground uplift in four episodes during Jan-Nov 2007, 2008-2009, Feb-Mar 2010 and Mar-May 2011, but also a temporal gap between the maximum uplift rate and the time of eruption in June 2011. The uplift was likely caused by pressurization of the magmatic system between 4-9 km depth. Data spanning the first 3 days of the eruption show ~1.5 m of deflation produced by two distinct sources at 4-6 km depth located 18 km from each other and up to 10 km from the eruptive vent – suggesting hydraulic connectivity of a large magma mush zone. An additional source of deflation is observed during the extrusive phase of the eruption (~2 m), with a slight source change in October 2011 correlated with changes in seismicity. TanDEM-X digital elevation models show ~220 m of uplift in the area of the eruptive vent interpreted as the intrusion of a shallow laccolith during the first 2.5 months of the eruption as well as time averaged lava discharge rates up to ~200 m3/s. Both the co-eruptive subsidence and the extruded volume time series have exponential trends that can be explained by a model of magma reservoir depressurization, gas exsolution, and conduit flow. After the end of the eruption, InSAR time series recorded ~0.9 m of ground uplift in two episodes in Mar. 2013-May 2015 and July 2016-Feb 2017, and produced by a source at ~6 km depth but in a different location than the pre- and co-eruptive deformation, while high-resolution InSAR time series (2 m/pixel) show ~2.5 m/year of subsidence during 2016 in the area of the shallow laccolith. The pre and post-eruptive inflation were related to both high and scarce seismicity respectively. We propose that these transient events are produced by magma injection into the plumbing system underneath the volcano and that they provide the heat and volatiles required to rejuvenate the crystal-rich mush that likely underlies the volcano.

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