After a period of earthquakes and crustal movements, on 19th of March 2021 a volcanic eruption started in Geldingadalir, a valley in Fagradalsfjall Mountain, located in the Reykjanes Peninsula (Iceland). The eruption started as a fissure eruption but quickly developed into a shield volcano eruption, characterized by low effusion rates and lava flow from a single crater. The lava discharge was periodic and in September 2021, when the eruption stopped, covered approximately 4,9 km2 of land with a volume of 150 million cubic meters (0,15 km3).

Three retention dikes and two diversion dikes were built near the eruption in order to divert the lava flow. The first two retention dikes were overtopped, while two diversion dikes diverted lavaflow into Nátthagi valley successfully towards the sea to preserve the existing road, which is of vital importance for the area. In June/July 2021 the third retention dike, located at the end of the Nátthagi valley was reached by the lava flow which stopped at its toe.

The project consists of monitoring the pressure excreted by the lava on the retention dike. The monitoring system has been composed by temperature sensors and SISGEO earth pressure cells, equipped with 700kPa vibrating wire pressure transducers. The instruments have been installed in the third retention dike, offering a complete analysis of the behavior of the lava flow and of the dike itself.

Thanks to VERKIS for this valuable reference!