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

A major challenge in using satellite interferometry (InSAR) for volcanic monitoring in the tropics is distinguishing volcano deformation from atmospheric noise. We reanalysed InSAR 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 (ECMWF-HRES). 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.