Using remote-sensing data for long-term hazard assessment due to fault movements in the Reykjanes peninsula, Iceland

In 2021, an eruptive episode started on the Reykjanes peninsula in the southwestern part of Iceland. To date (January 2026), at least 14 dike intrusions have occurred along this part of the mid-Atlantic plate boundary, 12 of which reached the surface in eruptions. The intrusive activity is accompanied by seismic activity and has also triggered earthquakes as large as M 5.6 along the boundary. All this activity has led to widespread surface faulting with associated hazards. Previous studies indicate that during such episodes, most of the six volcanic systems in the peninsula become activated, on the timescale of tens to a few hundreds of years. Some of these volcanic systems extend into cities and towns, including the eastern part of the capital area of Reykjavík.

There are different types of hazards and risks due to fault movements: a) Damage to houses and buildings on or near fault ruptures. b) Damage to infrastructures that cross active fault scarps, such as roads, pipelines, and powerlines. c) Fault movements can cause opening and dislocations of faults, which can be hazardous for people and livestock. d) Fault movements can cause the formation of sinkholes above the faults, which is also hazardous for people and livestock. e) Grabens can subside, sometimes below water-level, causing inundation of previously dry land. f) Fault movements can cause changes in borehole pressure, either increase or decrease, causing lack or overflow of water.

The Icelandic Meteorological Office currently works on a volcanic hazard and risk assessment for the entire Reykjanes peninsula. Communities and stakeholders can use it for planning in order to minimize societal disruptions due to such unrest periods. This includes a hazard assessment for fault movements, which are often associated with volcanic unrest, such as the one currently ongoing. This assessment is built upon work where multiple types of remote-sensing data, including aerial photographs, digital elevation models (DEMs), and InSAR images have been used for fault mapping, including faults that have recently been activated. The project also includes an assessment of how active different parts of the volcanic systems are. Such an assessment can be complicated, as the fractures and faults are located in different types of material (loose soil or lavas) of different ages. The long-term hazard assessment for fault movements will thus be a valuable tool to increase the resiliency of the society and its infrastructures due to such events.