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Measuring the rate of lava effusion by InSAR

Geoff Wadge(1)

(1) University of Reading, Harry Pitt Building, 3 Earley Gate, Reading, RG6 6AL, United Kingdom

Abstract

The rate at which lava emerges from a volcano is a fundamental property of the dynamics of the eruption. Intensive field measurements can capture this. However, for many, often cloud-covered, volcanoes with long-lived eruptions, spaceborne InSAR provides a potentially useful source of information. Repeated DEM creation at intervals allows the changing thickness of the lava flow field to be measured and incremental changes to calculate the volumetric lava flux rate. ERS data from (i) an andesitic lava dome eruption at Soufriere Hills, Montserrat , and (ii) a basaltic andesite lava flow-field at Arenal volcano, Costa Rica illustrate the method. There are two main limitations. Firstly, the height accuracy achievable on steep surfaces is of the order of 10m and so only thick lava flows or substantial compound fields can be usefully measured. Secondly, flowing or otherwise thermo-mechanically unstable surfaces that are active between interferogram pair acquisitions leads to decorrelation. The latter effect is particularly difficult on lava domes where the surface is extremely dynamic. Compound lava flow-fields are more tractable. The InSAR-measured rate of lava effusion at Arenal fits well with rates calculated by other methods over the last 30 years.

 

Full paper

Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry