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Radarpaper in Nature Communications veröffentlicht

Radarpaper in Nature Communications veröffentlicht

Deformation analysis using Sentinel-1 Radar data showed the spatial pattern of deformation and its acceleration corresponding to volcanic activities.
TerraSAR-X revealed morphological changes by sector collapse, material deposition, and subsequent erosion.

Precursor signals prior to Anak Krakatoa fatal eruption

On 22 December 2018, Anak Krakatau, an Indonesian island volcano collapsed its flank and triggered a deadly tsunami. Although the Anak Krakatau volcano was known to be active, individual observed anomalous signals were not interpreted as precursory to a volcanic eruption. Mahmud Haghshenas Haghighi and Mahdi Motagh, two researchers from the Institute of Photogrammetry and GeoInformation at the Leibniz University of Hannover, co-authored a new study published in the journal Nature Communications1. This comprehensive study employed ground-based and space-borne data to investigate the precursory activities of the Anak Krakatau volcano. Satellite data provided significant insight into the details of the precursory events.

Radar data acquired by Copernicus Sentinel-1 mission, highly penetrating through clouds and volcanic emissions, allowed delineating the outline of the volcanic island. The results indicated little variations in the first six months of the year 2018, but a raise in the island surface area during the six months prior to the collapse in December 2018. An increase in thermal activities evident in MODIS and Sentinel-2 satellite data also confirmed the start of a new activity period six months before the collapse. 

Deformation mapping in different geometries of the Sentinel-1 Radar data showed one-third of the island area had been creeping throughout a year before the failure with periods of accelerations corresponded to volcanic activities. Satellite thermal data revealed the increase in the volcanic activities within a few hours that lead up to the slope failure followed by volcanic eruptions. Ground-based seismic and infrasound instruments captured the landslide and eruption signals with a high temporal resolution. Shortly after the collapse, Sentinel-1 data helped outline the new perimeter of the island.

Furthermore, a comparison of high-resolution Radar images from the German TerraSAR-X mission shows the details of morphological changes following the sector collapse, material deposition, and subsequent erosion. The finding of this study provided a detailed picture of volcanic activities before the Anak Krakatau eruption. They have important implications for a better understanding of volcanic hazards and the development of early detection technologies at other volcanoes around the globe.

¹: Walter, T. R., Haghighi, M. H., Schneider, F. M., Coppola, D., Motagh, M., et al. (2019). Complex hazard cascade culminating in the Anak Krakatau sector collapse. Nature Communications, 10(1), 1-11.

Link to the paper:

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