Abstract
AbstractResolving changes in topography through time using accurate high‐resolution digital elevation models (DEMs) is key to understanding active volcanic processes. For the first time in a volcanic environment, we utilize very high‐resolution tri‐stereo optical imagery acquired by the Pleiades‐1 satellite constellation and generate a 1 m resolution DEM of Fogo Volcano, Cape Verde—the most active volcano in the Eastern Atlantic region. Point cloud density is increased by a factor of 6.5 compared to conventional stereo imagery, and the number of 1 m2 pixels with no height measurements is reduced by 43%. We use the DEM to quantify topographic changes associated with the 2014–2015 eruption at Fogo. Height differences between the posteruptive Pleiades‐1 DEM and the preeruptive topography from TanDEM‐X give a lava flow volume of 45.83 ± 0.02 × 106 m3, emplaced over an area of 4.8 km2 at a mean rate of 6.8 m3 s−1.
Highlights
Volcanic activity is among the fastest processes causing changes to the Earth’s surface, whether new volumes are added during effusive eruptions or catastrophically removed by explosive events and triggered landslides
The topographic approach, which constrains the changes in topography by differentiating preeruptive, coeruptive, and posteruptive digital elevation models (DEMs) [Stevens et al, 1999], can nowadays be considered the most suitable method to accurately quantify the volume of new volcanic deposits, especially when data are acquired by spaceborne Earth Observation (EO) platforms [e.g., Lu et al, 2003; Rowland et al, 2003; Bignami et al, 2013; Poland, 2014; Albino et al, 2015; Kubanek et al, 2015; Martino et al, 2015]
We evaluate the use of very high resolution (VHR) tri-stereo optical imagery from the Pleiades-1 satellite constellation for volcanological applications
Summary
Volcanic activity is among the fastest processes causing changes to the Earth’s surface, whether new volumes are added during effusive eruptions or catastrophically removed by explosive events and triggered landslides. The topographic approach, which constrains the changes in topography by differentiating preeruptive, coeruptive, and posteruptive digital elevation models (DEMs) [Stevens et al, 1999], can nowadays be considered the most suitable method to accurately quantify the volume of new volcanic deposits, especially when data are acquired by spaceborne Earth Observation (EO) platforms [e.g., Lu et al, 2003; Rowland et al, 2003; Bignami et al, 2013; Poland, 2014; Albino et al, 2015; Kubanek et al, 2015; Martino et al, 2015] These data sets provide densely spaced measurements of heights at relatively high temporal frequency (hours to days, if combined) and meter level vertical accuracy, without the need for direct field measurements. From the Pleiades-1 posteruption topography we subtract heights from a preeruptive DEM, obtained using spaceborne synthetic aperture radar (SAR) data from the TanDEM-X mission Such differencing provides the means to estimate the volume of the 2014–2015 lava flow with an unprecedented accuracy for Fogo Volcano [e.g., Richter et al, 2016]. Using SAR data acquired by the Sentinel-1a satellite, we apply SAR interferometry (e.g., InSAR) to measure the lava flow subsidence due to cooling and contraction in the months after its emplacement and compare this to the measured lava flow thickness
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