Mapping and visualizing lava flows of the Fagradalsfjall volcano in Iceland

Sofia Margarita DELGADO BALAGUERA

Master's thesis

Abstract:

The Fagradalsfjall volcanic system in Iceland erupted in March 2021 marking the end of a long dormancy period in the Reykjanes Peninsula. Mapping, analysing, and visualising volcanic hazards such as lava flows play an essential role in disaster risk management and increases general awareness of their possible danger. This research elaborated a time-series analysis to delineate the extent of the lava flows generated during the 2021 Fagradalsfjall eruption using Synthetic Aperture Radar and Object-based Image Analysis, validated and compared the delineation of the resulting lava flow outlines with existing reference data, and interactively visualised the lava flow field evolution. The calculated area of the lava flow path resulted in 4,3 km?, ten percent less than the area reported for previous delineations. The validation of the results indicated high correlation and coincidence with the reference data and displayed accuracies above 80%. The results of the application of the OBIA method on Sentinel-1 backscatter data revealed certain potential for lava flow mapping as they showed agreement with existing reference data, however, the outcomes should be evaluated carefully since factors such as spatial resolution, Synthetic Aperture Radar (SAR) geometrical distortions, and the OBIA segmentation scheme can influence the classification. The web application provides an interactive framework to communicate the results of the research. Further studies could make use of the lava flow delineation as inputs for lava modelling or as ground data for future eruptions of the Fagradalsfjall volcano. Furthermore, the contribution can support local authorities to promptly respond to lava flow potential danger.

Abstract:

The Fagradalsfjall volcanic system in Iceland erupted in March 2021 marking the end of a long dormancy period in the Reykjanes Peninsula. Mapping, analysing, and visualising volcanic hazards such as lava flows play an essential role in disaster risk management and increases general awareness of their possible danger. This research elaborated a time-series analysis to delineate the extent of the lava flows generated during the 2021 Fagradalsfjall eruption using Synthetic Aperture Radar and Object-based Image Analysis, validated and compared the delineation of the resulting lava flow outlines with existing reference data, and interactively visualised the lava flow field evolution. The calculated area of the lava flow path resulted in 4,3 km?, ten percent less than the area reported for previous delineations. The validation of the results indicated high correlation and coincidence with the reference data and displayed accuracies above 80%. The results of the application of the OBIA method on Sentinel-1 backscatter data revealed certain potential for lava flow mapping as they showed agreement with existing reference data, however, the outcomes should be evaluated carefully since factors such as spatial resolution, Synthetic Aperture Radar (SAR) geometrical distortions, and the OBIA segmentation scheme can influence the classification. The web application provides an interactive framework to communicate the results of the research. Further studies could make use of the lava flow delineation as inputs for lava modelling or as ground data for future eruptions of the Fagradalsfjall volcano. Furthermore, the contribution can support local authorities to promptly respond to lava flow potential danger.

Keywords

Fagradalsfjall eruption 2021, synthetic aperture radar, object-based image analysis, Sentinel-1, web application

Language used: English

Date on which the thesis was submitted / produced: 24. 5. 2023

Thesis defence

• Supervisor: RNDr. Jan Brus, Ph.D.

Palacký University Olomouc

Faculty of Science

Master programme / field:
Geoinformatics and Cartography / Geoinformatics and Cartography