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Inflation and deflation at the steep-sided Llaima stratovolcano (Chile) detected by using InSAR

2011; American Geophysical Union; Volume: 38; Issue: 10 Linguagem: Inglês

10.1029/2011gl047168

1944-8007

Hannes Vasyura‐Bathke, Manoochehr Shirzaei, Thomas R. Walter,

Landslides and related hazards

Llaima volcano, Chile, is a typical basaltic-to-andesitic stratovolcano in the southcentral Andes.Llaima had at least four explosive eruptions in the decade 2000 -2010, however little is known about the physical processes and magma storage at this volcano.In this study we present an InSAR deformation field at Llaima from 2003 -2008, covering both the post-eruptive and syn-eruptive periods.The satellite InSAR data are significantly affected by environmental decorrelation due to steep topography, snow and vegetation; because of this, we applied a model-assisted phase unwrapping approach.The analysis of these data suggests two main deformation episodes: subsidence associated with the posteruptive period, and uplift associated with the syn-eruptive period.Maximum summit subsidence and uplift are ∼10 cm and ∼8 cm, respectively.Through inverse modeling of both periods, a deflating and inflating magma body can be inferred, located at a depth of 4 -12 km, subject to a volume decrease of 10 -46 × 10 6 m 3 during the subsidence period, followed by a volume increase of 6 -20 × 10 6 m 3 during the uplift period.Therefore, this study presents the first evidence of magma-driven deformation at Llaima volcano, and suggests that eruption periods are associated with the inflation and deflation of a deep magma body that can be monitored by using space geodesy.