Abstract
In July and August 2019, two paroxysmal eruptions dramatically changed the morphology of the crater terrace that hosts the active vents of Stromboli volcano (Italy). Here, we document these morphological changes, by using 2259 UAS-derived photographs from eight surveys and Structure-from-Motion (SfM) photogrammetric techniques, resulting in 3D point clouds, orthomosaics, and digital surface models (DSMs) with resolution ranging from 8.1 to 12.4 cm/pixel. We focus on the morphological evolution of volcanic features and volume changes in the crater terrace and the upper part of the underlying slope (Sciara del Fuoco). We identify both crater terrace and lava field variations, with vents shifting up to 47 m and the accumulation of tephra deposits. The maximum elevation changes related to the two paroxysmal eruptions (in between May and September 2019) range from +41.4 to −26.4 m at the lava field and N crater area, respectively. Throughout September 2018–June 2020, the total volume change in the surveyed area was +447,335 m3. Despite Stromboli being one of the best-studied volcanoes worldwide, the UAS-based photogrammetry products of this study provide unprecedented high spatiotemporal resolution observations of its entire summit area, in a period when volcanic activity made the classic field inspections and helicopter overflights too risky. Routinely applied UAS operations represent an effective and evolving tool for volcanic hazard assessment and to support decision-makers involved in volcanic surveillance and civil protection operations.
Highlights
The easternmost island of the Aeolian Islands in southern Italy, is well known for its Strombolian, persistent low-energy, and short-lived explosive activity occurring with a time interval ranging from seconds to minutes from multiple vents located within the summit crater terrace [23,24,25]
As it was not possible to acquire GCPs for absolute positioning in the Stromboli crater terrace, we further improved the spatial accuracy of our georeferenced 3D point clouds using the Cloud Compare open-source software
The morphology of the crater terrace area is well represented by all the datasets and the comparison between the multitemporal digital surface models (DSMs) reflects new changes caused by the volcanic activity
Summary
Volcanoes are highly dynamic geomorphological features that shape the landscape through eruptions and erosional processes, both on a short- and long-term time scale (hours to tens of thousands of years). The topography of active volcanic areas represents the direct (lava flows, fallout deposits, pyroclastic density currents) or indirect (lahar, landslides, collapses) expression of eruptive activity. For this reason, observing volcanic activity and resolving morphological changes on active volcanoes through time is key to understanding active volcanic processes.
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