Reanalysis and (near) real-time inversion of deformation observations at Alaskan volcanoes

Abstract

Forecasting volcanic eruptions remains challenging due to the complexity and limited understand­ing of volcanic processes. However, recent studies have shown that integrating multidisciplinary data from past eruptions can improve forecasts for monitored volcanoes. The PREEVENTS project addresses this challenge identifying patterns prior, during or following volcanic eruptions on mul­tidisciplinary data. The project considers four disciplines: Geodesy, Petrology, Seismology and Gas/Geochemistry. This dissertation contributes with two novel tools to analyze geodetic data. The first tool exploits the amplitude from SAR imagery to quantify morphology changes during erup­tions. The tool has been verified with a synthetic case and validated with a dome growth episode for the 2011-12 eruption in Mount Cleveland. We apply this tool to the 2019-20 Shishaldin eruption finding elevation increases due to a scoria cone up to 30 m with a volume of 0.4 Mm3. The method detected elevation decreases due to the destruction of the cone after an explosive event and crater deepening when the volcanic activity decreased. The second tool is a Python-based object-oriented inversion framework for different types of geodetic data that implements elastic and viscoelastic models and two inversion approaches: a non-linear least squares algorithm and a Bayesian approach. We use the framework to find the most probable deformation sources for an inflation episode in Westdahl volcano and a deflation episode in Fisher Caldera. We find a spherical source in Westdahl at 7-8 km depth with a volume gain of 5-6 Mm3/yr and a spheroidal source at 4-6 km depth with a volume loss rate of 2-3 Mm3/yr. These tools are used to analyze geodetic observations for Shishaldin Volcano in the last 20 years. The results are synthesized with data from other disciplines to propose a conceptual model on Shishaldin Volcano for its last three eruptions. We propose a plumbing system composed of a shallow source at 2-4 km depth and a 10km long conduit that becomes narrower in the last kilometer.