Tectonic Activity and Volcanic Systems in Iceland

Iceland provides a rare natural laboratory for studying the dynamics of a divergent plate boundary exposed on land. The Mid-Atlantic Ridge bisects the island, giving rise to major rift zones that accommodate continual spreading and frequent magmatic intrusions. Volcanic systems such as those beneath Vatnajökull, the Reykjanes Peninsula and the Northern Volcanic Zone host a spectrum of eruptive styles, from effusive fissure eruptions to explosive central-volcano activity. Interactions between crustal stress, magma transport and surface deformation govern both the timing and character of eruptions. In parallel, high-enthalpy geothermal fields exploit the heat and fluids generated by these processes, creating coupled natural and anthropogenic deformation signals. Recent advances in geophysical monitoring, remote sensing and geochemical sampling have deepened our understanding of how pre-existing structures, dike emplacement and stress evolution control the onset and evolution of volcanic events in Iceland, with implications for hazard assessment and sustainable resource management worldwide.

Research from Nature Portfolio

Innovations in passive seismic methods have enabled indirect estimation of steam content in geothermal reservoirs. At the Hengill field, continuous seismic noise interferometry revealed a consistent annual reduction in wave velocity, which correlates with subsurface steam cap growth. This approach offers a non-invasive and cost-effective means to monitor reservoir dynamics. A drone-based aeromagnetic survey of the Bárðarbunga rift to the north of Vatnajökull ice cap has unveiled previously unrecognised faults and conjugate structures beneath Holuhraun. These buried lineaments align with the vents of the 1797 and 2014–15 eruptions, demonstrating that dormant structures can steer magma ascent and eruption loci. Detailed analysis of deformation and seismicity preceding the 2021 Fagradalsfjall eruption challenges conventional precursory models: after a phase of stress release and dyke emplacement, both ground deformation and earthquake rates declined in the days immediately before eruption, underscoring the complex interplay of tectonic unloading and crustal rheology.

Tectonic Activity and Volcanic Systems in Iceland publication trend

The graph below shows the total number of articles in tectonic activity and volcanic systems in iceland across all publications each year (not limited to Nature Index journals).

Technical terms

Divergent plate boundary: A tectonic margin where lithospheric plates move apart, allowing mantle material to upwell and form new crust.

Rift zone: A linear region of crustal extension characterised by faults and dikes, often hosting chains of volcanic vents.

Dyke: A tabular intrusion of magma that cuts across pre-existing rock layers, commonly feeding surface eruptions.

Transtensional: A combined tectonic regime involving both extension and strike-slip motion, producing oblique fractures and mixed faulting.

Seismic noise interferometry: A method that extracts seismic wave velocity information by cross-correlating ambient vibrations, without requiring active sources.

Aeromagnetic survey: The measurement of variations in the Earth’s magnetic field from an airborne platform to infer subsurface structural features.

Distributed acoustic sensing (DAS): A fibre-optic technique that records strain and seismic waves along the length of a cable, enabling high-density vibration sensing.

References

1. Steam caps in geothermal reservoirs can be monitored using seismic noise interferometry. Communications Earth & Environment (2023).
2. Pre-existing structural control on the recent Holuhraun eruptions along the Bárðarbunga spreading center, Iceland. Scientific Reports (2024).
3. Deformation and seismicity decline before the 2021 Fagradalsfjall eruption. Nature (2022).
4. Multi-Sensor Seismic Processing Approach Using Geophones and HWC DAS in the Monitoring of CO2 Storage at the Hellisheiði Geothermal Field in Iceland. Sustainability (2024).
5. Understanding the Seismic Signature of Transtensional Opening in the Reykjanes Peninsula Rift Zone, SW Iceland. Journal of Geophysical Research: Solid Earth (2024).
6. The eruption in Fagradalsfjall (2021, Iceland): how the operational monitoring and the volcanic hazard assessment contributed to its safe access. Natural Hazards (2023).