Reevaluating Volcanic Deformation Using Atmospheric Corrections: Implications for the Magmatic System of Agung Volcano, Indonesia

Abstract

A major challenge in using satellite interferometry (interferometric synthetic aperture radar) for volcanic monitoring in the tropics is distinguishing volcano deformation from atmospheric noise. We reanalyzed interferometric synthetic aperture radar time series from 2007–2009 from Agung volcano, Indonesia, which had previously been used as evidence for unrest. Using uncorrected data, we find an apparent velocity of 5.0±2.7 cm/yr consistent with previous reports, but we show that this signal is consistent with predictions of atmospheric contributions derived from weather models (European Centre for Medium-Range Weather Forecasts-High-Resolution). Following the correction, we find a velocity of 1.4±4.2 cm/yr and conclude that there was no significant deformation related to the inflation of a shallow magma source from 2007–2009. We discuss the implications for the inferred magma storage system at Agung and consider which other reported signals might have been wrongly attributed to deformation and should be reanalyzed.