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Laccolith deformation, pit craters, and caldera subsidence at Puyehue-Cordón Caulle, Chile (2011-2024): Integrating InSAR, high-resolution topography and optical imagery

Diego Lobos-Lillo (1), Alonzo Olitt (1), Matt Pritchard (1), Philipp P Ruprecht (2), Francisco Delgado (3), Felipe Aron (3)

  • Affiliations: (1) Department of Earth and Atmospheric science, Cornell University, Ithaca, NY, USA; (2) Department of Geological Sciences and Engineering, University of Nevada, Reno, USA; (3) Departamento de Ingenieria, Universidad de Chile, Santiago, Chile

  • Presentation type: Talk

  • Presentation time: Friday 11:15 - 11:30, Room R380

  • Programme No: 2.3.10

  • Theme 2 > Session 3

Abstract

The 2011-2012 Puyehue-Cordón Caulle eruption generated surface modifications that continue to evolve. While previous studies documented first-order deformation patterns including inflation from a magma chamber and uplift and subsidence of a laccolith, the spatiotemporal evolution of surface changes around the eruptive vent and 6km away at Puyehue volcano remains poorly constrained. We employ multi-temporal InSAR analysis spanning 2011-2024, coupled with high-resolution DEMs and optical images to quantify surface property changes. Our detailed analysis of the laccolith reveals the development of both extensional fractures and pit craters exhibiting distinct morphological evolution. The fracture network shows progressive development radiating from pit crater centers, with individual fractures extending 100-500m in length. Pit craters range from 10-50m in diameter and reach depths of 30m, demonstrating ongoing structural adjustment of the shallow magmatic system. Initial rapid subsidence of up to 19m/yr was observed in both the laccolith and tephra deposits until February 2013, followed by slower subsidence of all deposits until 2019, with tephra deposits reaching thicknesses of 10-50m. Independently, at Puyehue caldera, analysis of new Pleiades DEMs (0.5m) acquired in 2024 documents sustained but decreasing subsidence rates, transitioning from -7.7m/yr (2016-2019) to -2.4m/yr (2019-2024). This 40% reduction in subsidence rate, coupled with the progressive development of concentric ring fractures (2.5km in diameter), provides important constraints on the source mechanisms driving continued surface deformation within the caldera. We demonstrate how integrating multiple remote sensing datasets enables detailed characterization of post-eruption changes, with applications to monitoring active laccoliths at Usu volcano, Japan and Mount St. Helens.