About 2 million people live within 13 miles (about 21 km) of Masaya volcano in Nicaragua, and a Penn State team has used six years of satellite radar data to conclude that the volcano is fed by two separate magma sources. Lead author Lizzie Johnson, who earned her geosciences bachelor’s degree at Penn State in May 2026, and her colleagues reported the result in Geophysical Research Letters. The researchers reported no immediate danger to nearby communities.
Help yourself and the planet: The Cool Down makes it easy to help yourself while helping the planet, with smart, simple changes to save more and waste less in your everyday life.
We may earn a commission if you sign up.
Two signals from one caldera
The team tracked ground movement across 2018 to 2024 and found two patterns that do not match each other. Inside the caldera, the ground first subsided and then began to rise. The release, republished by ScienceDaily on Oct. 19, notes that the satellite record shows the ground inside the caldera first receding, then rising again. Penn State’s account, in its university news story on the study, says the researchers interpreted the rise as the main reservoir inflating, possibly because new magma is entering a deep source.
The area around the active Santiago crater and its lava lake behaved differently. It sank for the entire study period, independently of the transition to inflation of the main reservoir, which the team reads as a shallower reservoir losing magma. The study’s title, “Double Trouble: Two Active Magma Reservoirs Identified at Masaya Volcano, Nicaragua, Using Satellite Geodesy,” was published under DOI 10.1029/2026GL123214. Johnson explained the logic of the subsidence signal plainly: “When it’s subsiding, that means that there’s probably magma draining away from the volcano.”
How Sentinel-1 radar sees the ground move
The data came from Sentinel-1, a radar satellite that observes Masaya about once every 12 days. The method, interferometric synthetic aperture radar or InSAR, compares radar images taken at different times to detect tiny changes in surface elevation. A UN-SPIDER summary of Sentinel-1A deformation mapping describes the approach as comparing two or more radar images, with ground movement appearing as striped patterns called interferograms, and credits it with a drastic improvement over earlier satellites.
Young Cheol Kim, who completed his Penn State geosciences doctorate in summer 2026, pointed to a practical advantage: “Cloud penetration is important for volcanoes because many of them, like Masaya, are in tropical areas.” Christelle Wauthier, a Penn State professor of geosciences and computational sciences hub director at the Institute for Computational and Data Sciences, supervised Johnson’s research. Funding came from U.S. National Science Foundation awards 1945417 and 2523375, plus computing resources from Penn State’s Institute for Computational and Data Sciences. Johnson has since started a doctoral program in Earth sciences at the University of Hawaii at Manoa, where she plans to study Kilauea using seismic waves.
A volcano that has not produced a major flow since 1772
Masaya’s last major lava flow came in 1772, according to Johnson, but the volcano is far from quiet. Johnson said its persistent degassing often produces dangerously high concentrations of sulfur dioxide, and the caldera is a national park and popular tourist destination just outside the capital, Managua.
The Smithsonian Institution’s Global Volcanism Program entry for Masaya puts the volcano about 20 km southeast of Managua, at 594 meters (1,949 feet) elevation, inside a 6 by 11 km basaltic caldera whose walls reach 300 meters. It records that a lava lake formed in Santiago crater in December 2015, and that a landslide covered the lake in March 2024, which places the Santiago signal in the same crater the Penn State team found sinking.
What the finding does and does not say
Two reservoirs is a claim about structure, and the researchers worded it as an interpretation of what the surface did over 2018 to 2024.
The result is an interpretation of surface motion, and the study frames it that way. A sinking crater and a rising caldera suggest two plumbing elements, but satellites measure the ground, not the magma itself, and the Penn State account gives no figures for how many centimeters the ground moved or when the trend reversed. Those numbers sit in the paper. The study also covers one stretch of time only, six years of observations at a volcano whose lava lake has come and gone over decades, so the team stresses that continued monitoring is needed to say whether the inflation under the caldera continues, stalls or reverses, and whether the shallow source near Santiago keeps draining.
Johnson said the observations help scientists understand how magma moves beneath Masaya and “may improve monitoring and eruption forecasting in the future,” and that further long-term geodetic and modeling studies will give a more thorough picture. Kim added that continuous monitoring allows researchers to understand the baseline activity of the volcano, which is what makes a later change recognizable. For the 2 million people within 13 miles, the study’s practical message is that the volcano is being watched from orbit every 12 days.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
Help yourself and the planet: Get The Cool Down →
We may earn a commission if you sign up.
More from Morning Overview
- Lake Powell sank to a record 3,517 feet, nearing the level that stops Glen Canyon Dam’s turbines
- Seven of Earth’s nine planetary boundaries are breached, and all seven are worsening
- The NSA says three phone features should be off whenever you aren’t using them
- Hurricane Hunter radar shows four warning signs that a tropical cyclone is about to strengthen, a University of Miami study found
