Characterising magmatic domains from a synthesis of global satellite radar measurements

The type of deformation measured using space-based geodesy is distinctive due to the unique temporal and spatial range of the method. Compared to ground-based geodetic networks, satellite radar is more likely to detect deformation 1) kilometres away from recently active vents, 2) with very large (>1000 km²) spatial footprints or 3) associated with non-eruptive processes. Survey-mode measurements of deformation in volcanic areas have also extended the scope of volcano geodesy to encompass deformation at volcanoes where active magmatic systems had not previously been identified, and non-observation of deformation associated with eruption. Such 'baseline' observations have implications for our understanding of how deformation can contribute to hazard forecasts, especially at volcanoes where a lack of monitoring data makes the development of informed physics-based models challenging. It also provides a data set that contains unique information about the characteristics of magma storage in different tectonic settings and at different stages of the eruption cycle.

Here, we discuss historical satellite radar measurements of volcano deformation, drawing on the Smithsonian Institution Volcanoes of the World database and the Centre for the Observation and Modelling of Earthquakes, Volcanoes and Tectonics volcano deformation catalogue, as well as recent CosmoSkyMed and Sentinel-1 observations from Latin America. To investigate global systematics in magma storage conditions, we first characterise the impact of measurement method limitations. This allows us to assess which patterns in global deformation reflect real features of magma storage. Although the depth distribution of inferred deformation source locations is affected by measurement limitations, the lateral distribution of deformation signals in relation to volcanic edifices provides evidence of the extent of active magmatic domains. We estimate that 24% of potentially magmatic deformation signals are located > 5 km from the nearest active volcanic vent.