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The uplift and subsidence of the Lascar crater floor, and the resulting fracture pattern analyzed by satellite stereo photogrammetry and 3D printed mould analog experiments

A sudden eruption occurred in December 2022 at Lascar, one of the most popular volcanoes for tourists in Chile. Following the eruption, lava emplacement was observed in summit crater of Lascar. Due to volcanic activity and inaccessibility, we acquired a series of Pleiades tri-stereo satellite images covering this unrest episode. We generated high resolution point clouds and orthomosaics from the satellite images using photogrammetric approaches. We analyze point clouds to quantify morphological and structural details and changes. We found that the crater floor initially uplifted due to lava extrusion and rockfall deposition, and subsequently the crater floor subsided and formed a funnel in the center. To understand the mechanical factors controlling the uplift and subsidence, we designed a novel set of analogue experiments using sand-plaster mixtures to simulate lava extrusion and subsidence from same conduit. We account for topographic effects by running experiments on flat plate and 3D printed mould of the Lascar crater, respectively. We use 2D digital image correlation method to record and visualize displacements during extrusion and subsidence. The results show that extrusion and subsidence occurs along distinct shear faults, which are constrained by conduit diameter and represented as concentric fractures at surface. We develop a conceptual model that lava extrusion is affected by withdrawal from the conduit, forming a funnel-shaped surface depression associated with inward-dipping radial erosion gullies. Thus, combining satellite observations and analogue models help to identify the position and dimension of the underlying conduit, which is essential for understanding future activity of Lascar volcano.

Details

Author
Lun Ai1, Thomas Walter1, Felipe Aguilera2
Institutionen
1GFZ German Research Centre for Geosciences, Germany; 2Department of Geological Sciences, Universidad Católica del Norte, Antofagasta, Chile
Veranstaltung
GeoSaxonia 2024
Datum
2024
DOI
10.48380/84q4-xb82