ALBERT

Description: Determining outline, volume and effusion rate during an effusive volcanic eruption is crucial as it is a major controlling factor of the lava flow lengths, the prospective duration and hence the associated hazards. We present for the first time a multi-sensor thermal-and-topographic satellite data analysis for estimating lava effusion rates and volume. At the 2021 lava field of Cumbre Vieja, La Palma, we combine VIIRS + MODIS thermal data-based effusion rate estimates with DSMs analysis derived from optical tri-stereo Pléiades and TanDEM-X bi-static SAR-data. This multi-sensor-approach allows to overcome limitations of single-methodology-studies and to achieve both, high-frequent observation of the relative short-term effusion rate trends and precise total volume estimates. We find a final subaerial-lava volume of 212×106±13×106m3 with a MOR of 28.8 ± 1.4 m3/s. We identify an initially sharp eruption-rate-peak, followed by a gradually decreasing trend, interrupted by two short-lived-peaks in mid/end November. High eruption rate accompanied by weak seismicity was observed during the early stages of the eruption, while during later stage the lava effusion trend coincides with seismicity. This article demonstrates the geophysical monitoring of eruption rate fluctuations, that allows to speculate about changes of an underlying pathway during the 2021 Cumbre Vieja eruption.

Description: Flood monitoring in arid regions is challenging using Synthetic Aperture Radar (SAR) due to the similar backscatter of water and dry sand in surrounding areas. Since textural information is abundant in SAR images, this study investigates the added value of texture in SAR-based flood detection by providing it as auxiliary information for flood delineation. Results show that texture enhanced SAR images in VH polarization substantially underpredicts the flooded area, so adding texture does not improve the classification accuracy. However, using both polarization (VV and VH) produce ~26% higher overall accuracy for flood detection in arid regions.

Description: Up-to-date information on the outline, volume and effusion rate during an effusive volcanic eruption is crucial as it is a major controlling factor of the lava flow lengths, the prospective duration and hence the associated hazards. Here, we present a multi-sensor approach combining thermal and topographic satellite data for estimating lava effusion rates and volume. We investigated the large 2021 volcanic eruption at Cumbre Vieja, La Palma and we combined MODIS and VIIRS thermal data-based effusion rate estimates with digital surface model (DSM) analysis derived from bi-static TanDEM-X synthetic aperture radar (SAR) and optical-tri-stereo Pléiades data. Advantage of this multi-sensor approach is to achieve both, high-frequent observation of the relative short-term effusion rate trends and precise total volume estimates. Our results show a final subaerial lava volume of 212x106 ± 13x106 m³ with a mean output rate (MOR) of 28.8±1.4 m³/s. The 2021 Cumbre Vieja eruption was characterized by an initially sharp eruption rate peak, followed by a gradually decreasing trend, and interrupted by two short-lived peaks in mid and in end November. Comparison with independent seismic observations show a high eruption rate accompanied by weak seismicity during the early stages of the eruption, while during later stage the lava effusion trend coincides with seismicity. We will demonstrate that the geophysical monitoring of eruption rate fluctuations allows to speculate about changes of an underlying pathway during the 2021 Cumbre Vieja eruption.