Reviewed by Lexie CornerApr 25 2025
According to a study published in Science, researchers from the California Institute of Technology identified a mechanism that can provide warnings of lava eruptions up to 30 minutes in advance by collecting data using distributed acoustic sensing technology.
Jiaxuan Li and a colleague in Iceland with a lava eruption in the distance. Image Credit: V. Hjörleifsdottír
The Reykjanes Peninsula, located on the southwestern tip of Iceland, is a volcanically active region with a dense population. In 2024, sensing technology developed by Caltech was installed in the area to monitor the movement of subterranean magma and its eruption onto the surface as lava.
The study demonstrates that distributed acoustic sensing (DAS) can be a useful method for studying volcanic activity and providing early warnings to the public.
The research was conducted in the laboratory of Zhongwen Zhan (PhD '13), professor of geophysics, Clarence R. Allen Leadership Chair, and director of the Caltech Seismological Laboratory.
Since November 2023, the Reykjanes Peninsula has experienced eight lava eruptions, some of which were large enough to threaten local communities. While Iceland is known for its volcanic activity, researchers believe this region is entering a period of heightened volcanic activity that may last for several years.
To further investigate, Zhan and his team collaborated with Icelandic scientists and the telecommunications company Ljósleidarinn to deploy DAS sensors across the peninsula for a year. The goal was to better understand volcanic activity and develop an eruption early warning system.
The deployment was extremely fast. We were able to set up our system on a 100-kilometer-long fiber cable within 10 days after a substantial magma intrusion event on November 10, 2023. About a month later, we recorded the first eruption with our system. This was a major international collaboration with real-world impact.
Jiaxuan Li, Study First Author and Assistant Professor, University of Houston
DAS works by directing lasers into existing underground fiber-optic cables, such as those used for internet connectivity. As vibrations pass through the cable, caused by events like earthquakes or traffic, the laser light undergoes a phase change. By measuring this phase shift, researchers can obtain data about the passing waves, making a 100-kilometer cable equivalent to a line of hundreds of traditional seismic sensors.
Volcanic activity also produces underground deformations as magma rises from shallow chambers. The pressure buildup can cause the magma to erupt to the surface through fissures called dikes. DAS is capable of tracking subsurface movement with precision on the order of millimeters in real-time, offering greater accuracy than GPS or satellite imagery.
During the investigation, DAS collected data on volcanic activity underground, monitoring the Earth’s expansion as magma moved. Using this data, the team developed a preliminary early-warning system that provided up to 30 minutes or several hours of notice before an eruption, depending on the type of magma intrusion.
Seismologist Vala Hjörleifsdóttir from Reykjavik University, who was involved in developing an eruption early warning system in Iceland, collaborated with the Caltech team. The system was crucial in monitoring a potentially dangerous eruption site near Grindavik, which posed a threat to thousands of residents. When the DAS sensors were installed, Hjörleifsdóttir worked with the team to identify signs in the data that indicated an imminent eruption.
Li recalled, “One day, in August 2024, we were in a group meeting at Caltech, and my phone started going off with the early warning alert. Twenty-six minutes later, Vala emailed us that the eruption had actually happened and that they had sent out an evacuation warning.”
Zhongwen Zhan added, “This is the most active volcanic system in Iceland. In addition to the need to provide advance warnings before an eruption, the project is scientifically interesting because we saw more magma intrusion events there than we originally thought, ones that do not come up to the surface. There is a lot more work to do, and all volcanoes are different, but DAS provides us a new capability to see things we could not before. Our project is also a great example of the power of international collaboration.”
Coauthors include Li, Hjörleifsdóttir, and Zhan, along with Ettore Biondi, Qiushi Zhai, Shane Zhang, Xiaozhuo Wei, and Elijah Bird (MS '24) of the Caltech Seismo Lab; Elías Rafn Heimisson (former Caltech postdoctoral scholar) and Halldór Geirsson of the University of Iceland; Simone Puel, former Caltech postdoctoral scholar now at Moody’s; and Andy Klesh of the Jet Propulsion Laboratory, which Caltech manages.
The Gordon and Betty Moore Foundation, the National Science Foundation (NSF), and the NSF Center for Geomechanics and Geohazard Mitigation funded the research.
Journal Reference:
Li, J., et al. (2025) Minute-scale dynamics of recurrent dike intrusions in Iceland with fiber-optic geodesy. Science. doi.org/10.1126/science.adu0225.