This 3D DOM shows an extension fractures field within the Krafla Fissure Swarm in Northern Volcanic Zone of Iceland. The 100m x 200m area is marked by the presence of a set of very long and wide (ranging from 0.3 m up 4 m) extension fractures cutting through horizontal, Holocene-age, 12-ka-old basaltic lavas (Saemundsson et al., 2012). The fractures are parallel or sub-parallel to each other, with an about N-S trend, and show a curved shape in the central part of the model. Furthermore, the fracture located farthest away from the road gradually transitions to a normal fault. Tectonic sinkholes are also present, aligned along the direction of the extension fracture. A close-up of the fractures reveal the tipycal zig-zag pattern of their borders, due to the columnar jointing of the lavas during cooling; piercing points can be clearly observed (Bonali et al., 2019). The fracture are the results of the extensional tectonic regime affecting the Northern Volcanic Zone of Iceland, where the overall spreading directions is about N106°, with an opening of about 2 cm/yr (Hjartardóttir et al., 2016); this area has been subjected to rifting events during the Krafla Fire (1975-1984 A.D.) when dykes propagating to the north, might have also contributed to fracture opening.
All the area is affected by periglacial morphologies coverying the underlying basaltic lava flow; known as ‘pingo’, they are formed in response to the growth of ice lenses within the soil.
Credits: UAV-based survey and 3D DOM by Fabio L. Bonali, funding is from MIUR project ACPR15T4_00098 (http://argo3d.unimib.it/). Description by Alessadro Tibaldi and Federico Pasquaré Mariotto.
- Bonali, F. L., Tibaldi, A., Marchese, F., Fallati, L., Russo, E., Corselli, C., & Savini, A. (2019). UAV-based surveying in volcano-tectonics: An example from the Iceland rift. Journal of Structural Geology, 121, 46-64.
- Hjartardóttir, R., Einarsson, P., Magnusdóttir, S., Bjornsdóttir, Þ. and Brandsdóttir, B. (2016) Fracture systems of the Northern Volcanic Rift Zone, Iceland: an onshore part of the Mid-Atlantic plate boundary. In: Wright, T. J., Ayele, A., Ferguson, D. J., Kidane, T., Vye-Brown, C. (eds), Magmatic Rifting and Active Volcanism. Geological Society, London, Special Publications, 420, 297-314.
- Mariotto, F. P., Bonali, F. L., & Venturini, C. (2020). Iceland, an Open-Air Museum for Geoheritage and Earth Science Communication Purposes. Resources, 9(2), 14.
- Saemundsson, K., Hjartarson, A., Kaldal, I., Sigurgeirsson, M.A., Kristinsson, S.G. and Vikingsson, S. (2012) Geological map of the Northern Volcanic Zone, Iceland. Northern Part 1: 100.000. Reykjavik: Iceland GeoSurvey and Landsvirkjun.