UC San Diego

In active volcanic regions, ground displacement measurements can be used to detect signals of a changing magma source. This thesis presents ground displacement measurements at Okmok Volcano from both Interferometric Sythetic Aperture Radar (InSAR) and Global Positioning System (GPS) data from late 2010 through the present. Comparing the data sets illuminates complications that InSAR presents when applied to a region with high seasonal variability.

Okmok is one of the most active volcanoes in the Aleutian island arc and recently erupted explosively in 2008. The data presented show that Okmok's ground surface has inflated over the data interval, indicating recharge of its magma storage. The radial symmetry of the inflation pattern on Okmok suggests that the magma source causing the inflation can be represented by a Mogi source model. Using our measurements of the volcano's surface deformation, we use the Mogi model to invert for for the magma chamber's best fit depth and volume change over time. Doing so results in an estimated magma chamber depth of ~3.6 kilometers and a time series of volume change that ends with ~0.05 cubic kilometers of cumulative growth.