Inflation of Okmok volcano during 2008 to 2020 from PS analyses and source inversion with finite element models

Abstract:

Okmok volcano, located on northeastern Umnak Island along the eastern end of the Aleutian island arc, is one of the most active volcanoes in Alaska. Okmok has produced multiple eruptions in the past century. The most recent, which occurred during July-August of 2008, was the most explosive eruption since the early nineteenth century. In the years following the 2008 eruption, Global Navigation Satellite System (GNSS) and Interferometric Synthetic Aperture Radar (InSAR) observations indicate that Okmok has inflated at a variable rate of 40-195 mm/yr. In this study, we investigate the posteruptive deformation of Okmok (2008-2020) using InSAR and GNSS. L-band ALOS-2, C-band Sentinel-1/ Envisat and X-band TerraSAR-X data are analyzed with Persistent Scatterer (PS) InSAR method. The deformation time series calculated from InSAR and GNSS are assimilated into finite element models (FEMs) using the Ensemble Kalman Filter (EnKF) to track the evolution of the magma system through time. The deformation time-series, estimated magma accumulation, and stress changes are compared with those during the last inter-eruption period (1997-2008), providing critical information on the probability of next eruption.