Ground movements beneath Nicaragua’s Masaya volcano point to two magma reservoirs behaving differently, offering scientists a clearer picture of an active volcano near roughly 2 million people.
The findings come from satellite radar observations spanning January 2018 through February 2024. Researchers identified a shift from sinking to rising ground north of Santiago crater, while the area immediately around the crater continued to deflate.
The team interpreted the contrasting movements as evidence of a deeper reservoir gaining magma and a separate, shallower reservoir losing it. The researchers published the study in Geophysical Research Letters on July 23, 2026.
About 2 million people live within 13 miles of Masaya, near Nicaragua’s capital, Managua, Penn State said. The volcano also attracts tourists to its national park and lava lake.
“These observations help scientists better understand how magma moves beneath Masaya and may improve monitoring and eruption forecasting in the future,” lead author Lizzie Johnson said in Penn State’s announcement.
The satellite record showed that ground north of Santiago crater moved about 3 centimeters away from the satellite between 2018 and mid-2022. The direction then reversed through the end of the study period, the researchers found.
Their modeling placed the deeper source near the center of Masaya’s caldera at approximately 3,200 meters below ground. They attributed the persistent deflation around Santiago crater to another reservoir at roughly 200 meters deep.
Those depths reflect the team’s modeling of surface movements. The satellites measured changes in the ground rather than directly observing underground magma.
The team used interferometric synthetic aperture radar, or InSAR, to compare satellite measurements over time. InSAR allows researchers to track surface changes through clouds, an advantage in tropical areas such as Masaya, Penn State explained.
The university said the researchers identified no immediate danger to surrounding communities from their observations. Their findings concern the volcano’s underground behavior during the study period and do not provide a timetable for a future eruption.
Continued monitoring could help researchers distinguish ordinary activity from changes that warrant closer attention, according to Penn State.
