On November 13, early estimates revealed the vertical shifts caused by the dike’s movement from Friday afternoon into Saturday morning. These displacements were calculated using a blend of ICEYE and COSMO-SkyMed pixel offset tracking results.
Insightful Research Published in *Science* by University of Iceland and Icelandic Meteorological Office Scientists
On November 10, 2023, the quaint town of Grindavík, Iceland, faced an urgent evacuation. A surge of molten magma flowed unexpectedly into a magma-filled crack beneath the town, triggering widespread geological changes. An international team of scientists has since unveiled the mechanics behind this rapid intrusion in a new study published in the esteemed journal *Science*.
Freysteinn Sigmundsson, a geophysicist at the University of Iceland and one of the lead authors of the study, stated, “The vertical sheet intrusion created during the evacuation is an astonishing 15 kilometers long and penetrates the Earth’s crust at depths ranging from one to five kilometers.”
He added, “This intrusion measures up to 8 meters in width. On the surface, significant fault movements and cracking resulted in extensive damage to both infrastructure and property, all within a span of approximately six hours.”
Dr. Michelle Parks, a volcano deformation specialist at the Icelandic Meteorological Office and another lead author, remarked, “By the evening of November 10, our initial estimates of the magma inflow rate to the dike were alarmingly high. At first, we suspected an error in the data due to the extreme figures. However, our analysis confirmed the accuracy of both the input data and the modeling outcomes.”
A Detailed Study on Crustal Deformation
The findings articulated in *Science* hinge on meticulous observations and interpretations of ground movement patterns, which were carefully monitored through seismic data.
“The insights garnered from this event shed light on how exceptionally long magma-filled cracks, sometimes exceeding tens of kilometers, can emerge. This phenomenon is driven by large fractures at the boundary of subterranean magma reservoirs, combined with extensional forces that build up over centuries—often due to the natural process of plate tectonics,” Sigmundsson explained.
He suggested that these extensional forces can effectively channel magma into existing cracks.
In the months following the initial incident, smaller-scale magma intrusions appeared in Grindavík during December 2023 and January 2024. In these cases, the magma culminated in hazardous fissure eruptions that further devastated the town. Although the flow of magma during the eruptions was visually striking, the volume of magma in motion on November 10, when no eruption occurred, was significantly greater. This disparity can be attributed to the extensional forces in the crust, as well as varying pressures needed to trigger magma flow – the initial failure of the magma accumulation area in November required a substantially greater force compared to the subsequent events.
Illustration of the Grindavík dike and a proposed magma domain, indicating where magma accumulated before the intrusion on November 10, 2023. The dike propagated rapidly beneath the Sundhnúkur crater row and the town of Grindavík, triggering fault motion and surface cracking, with surface projections of the dike and the crustal cross section marked by red dashed and gray solid lines, respectively.