Post eruptive source modeling for Okmok Volcano, Alaska using GPS and InSAR

Abstract

Okmok volcano is one of the most active volcanoes in the Aleutian Island chain, showing significant non-linear deformation as it progresses through eruption cycles. Okmok most recently erupted in July 2008, creating a new cone (~250m in height) and greatly changing the topography inside the caldera. Due to these changes within the caldera and magma system, new modeling of the volcanic source was completed. This study compiles both GPS and SAR measurements to constrain the post eruptive behavior, examines the possible changes below the surface, and explores modeling and optimization techniques. With continuous and campaign GPS stations and L-band radar imagery from the JAXA ALOS PALSAR satellite spanning August 2008 to October 2010, a variety of source models were tested and a best fit source model for the post eruptive behavior was found. Previously, a simple Mogi model was used in describing the behavior seen at Okmok, but post eruptive analysis showed a Double Mogi source for the initial first year of refilling. A 2 Mogi model did provide a better fit for the second year of deformation, but residual features due to compaction and erosion may have affected the modeling. These multiple Mogi models should be tested in future studies at Okmok and other shallow magma systems.