This 3D model has an aerial extent of about 600 x 250 m and is located within the Krafla Fissure Swarm in northern Iceland. It displays two, N10°-striking parallel extension fractures, with dilation ranging from 0.5 to 5 m, that transition to a series of tectonic sinkholes towards the north. These are circular to ellipse-shaped depressions, the latter with their axis parallel to the trend of fractures. A tectonic sinkhole forms wherever an underlying fracture has not propagated up to the surface, but its presence at depth has led to the collapse of poorly-consolidated to non-consolidated surficial deposits. These types of depression are reminiscent of those found in karst environments, but in this case they are associated with tectonic and volcanic processes. In particular, the tectonic sinkholes shown in the model have been interpreted as due to two rifting-related seismic events that took place in 1975–1976 and in 1978 along the Krafla Fissure Swarm. During such events, the sinkholes were generated in unconsolidated sediments overlying Holocene basaltic flows (Ferril et al., 2011); their diameter ranges from 2 up to 15 m.

Credits: UAV-based surveys and 3D DOM by Fabio Marchese; funding from MIUR project ACPR15T4_00098 ( Model descripition by Alessandro Tibaldi and Elena Russo.


  • Ferrill, D. A., Wyrick, D. Y., & Smart, K. J. (2011). Coseismic, dilational-fault and extension-fracture related pit chain formation in Iceland: Analog for pit chains on Mars. Lithosphere, 3(2), 133-142.