Stow or Blow: The Perspective from Global Satellite Observations of Deformation.

Abstract:

Satellite imagery covers volcanoes globally throughout their eruptive cycles, independent of ground-based monitoring and thus InSAR can give information on both intrusive and extrusive processes at a large number of volcanoes in a range of tectonic settings. Not all deformation is followed by an eruption, nor are all eruptions preceded by measureable deformation. In many cases volcanic deformation is linked to magma intrusion, instability of the volcanic edifice or changes in the hydrothermal system.

Here we provide a summary of global observations of volcano deformation and carry out a probabilistic analysis of the link between deformation and eruption. We show that, of the 198 volcanoes systematically observed for the past 18 years, 54 deformed, of which 25 also erupted. In terms of assessing eruption potential, this substantial proportion of deforming volcanoes that also erupted (46%), together with the very high proportion of non-deforming volcanoes that did not erupt (94%) shows that deformation status represents ‘strong’ evidential worth. From the perspective of the growth of continental crust, it demonstrates that roughly half of all deformation-generating episodes occurred at volcanoes with no recent eruptions.

 Next, using a larger catalogue of 540 volcanoes observed for 3 years, we demonstrate how this eruption–deformation relationship is influenced by tectonic, petrological and volcanic factors. Deformation and eruption are most directly linked (a higher PPV) for hotspot regions (0.33), basaltic (0.29) and andesitic compositions (0.34) and most weakly linked for rhyolite/dacite compositions (0.17), calderas (0.25) and rift settings (0.13). This indicates that tectonic setting and crustal stress state play primary roles in determining the proportion of subsurface and extrusive events.

Satellite technology is rapidly evolving and routine monitoring of the deformation status of all volcanoes from space is anticipated, meaning probabilistic approaches will increasingly inform hazard decisions and strategic development, and could also be used to inform the debate on continental growth.