Regional Scale Volcano Deformation and Unrest: Insights from InSAR Surveys in Latin America
Ebmeier, Susanna1; Biggs, Juliet1; Mather, Tamsin2
1University of Bristol, UNITED KINGDOM; 2University of Oxford, UNITED KINGDOM
InSAR measurements have now been made at over a hundred volcanoes worldwide and have illuminated a diverse range of magmatic, hydrothermal and edifice building processes. Relationships between deformation and volcanic unrest are not straight forward: the majority of observations of deformation made thus far did not occur during, immediately before or after eruption. A growing number of measurements capture a lack of deformation during volcanic eruptions, for example in Central America, where the lack of magmatic deformation during ALOS-1's period of operation was statistically significant. Quantifying the relationship between deformation and unrest therefore requires a systematic approach to InSAR surveys, where both deformation and a lack of deformation are reported and analysed.
The strengths and limitations of InSAR vary in different topographic, environmental and tectonic settings. InSAR measurements are inhibited by dense vegetation, sporadic snow cover, frequent explosions or steep topography. Instrumental considerations such as radar wavelength and spatial and temporal resolution also affect the character of processes that are measurable with InSAR. For example, the different properties and strengths of ALOS, RadarSat and TerraSAR-X data have allowed us to draw out different characteristics of deformation at Volcán Arenal, Costa Rica.
We present results from systematic surveys of volcano deformation in the Northern Andes, the Lesser Antilles and Central America and place the ratios of deformation to unrest in global context. We use this dataset as a basis for discussion of a) the applicability of InSAR to measuring regional differences in magma storage and ascent and b) the potential of InSAR as an operational volcano monitoring tool.