Scientists say Nicaragua’s “Mouth of Hell” volcano could be showing early signs of renewed activity.
Researchers have detected evidence that two magma chambers beneath the active Masaya volcano are being replenished.
Masaya lies only 13 miles (20km) from Managua, Nicaragua’s capital, home to around two million people.
The volcano also draws thousands of visitors each year, many hoping to glimpse the glowing lava inside its Santiago crater—a dramatic feature behind its ominous nickname.
Because of its location and persistent activity, the possibility of an eruption remains a serious concern. A new study has now identified signs of movement deep beneath the volcano.
The researchers found no evidence of an immediate threat, but their results indicate that the magma system beneath the “Mouth of Hell” is more intricate than previously believed.
Mapping the network of underground magma channels and reservoirs could help scientists recognize the changes that may signal an approaching eruption.
Lead researcher Lizzie Johnson of Penn State University said: “Having a thorough understanding of Masaya’s volcanic activity and its related hazards is critical.”
Masaya volcano, nicknamed the “Mouth of Hell” because of its lava-filled crater, may be showing signs of renewed activity, scientists have warned (file image)
Masaya is an unusually complicated volcanic system, featuring craters within craters as well as sinkholes created when underground magma chambers emptied.
That unusual structure means scientists still have only a limited understanding of the tunnels and magma chambers hidden below the surface.
The lack of clarity makes it more difficult to interpret the small changes that could reveal whether an eruption is approaching—an important challenge for a popular tourist site so close to Managua.
“Although Masaya last produced a major lava flow in 1772, its persistent degassing often produces dangerously high concentrations of sulphur dioxide volcanic gas,” Ms Johnson said.
The volcano has also experienced a number of explosions during the past five decades. None has caused injuries so far, but scientists remain determined to monitor the volcano closely.
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For the study, published in the journal Geophysical Research Letters, the team analyzed observations collected by the Sentinel-1 satellite.
Sentinel-1 flies over Masaya every 12 days, allowing researchers to track subtle changes in the ground as magma shifts beneath the volcano.
Ms Johnson explained: “When it’s subsiding, that means that there’s probably magma draining away from the volcano—but once the ground starts uplifting again, that can mean that there’s potentially new magma moving in.”
From 2018 through the middle of 2022, satellite measurements showed that land around the Masaya Central Reservoir, north of Santiago crater, dropped by roughly 1.2 inches (3cm).
The sinking suggests that magma had drained from the reservoir beneath the surface, producing a process known as deflation.
Active Masaya volcano is located just 13 miles (20km) from Managua, Nicaragua’s capital, where around two million people live—making any potential eruption a serious concern
The researchers found that the ground of the caldera first receded and then rose again (illustrated), suggesting that there could be two more active magma chambers beneath the surface
However, from 2022 to 2024, the ground started to rise once more, suggesting that the reservoir was once again filling with magma.
Strangely, the area directly around the Santiago crater and its lava lake deflated over the whole six-year period.
According to the researchers, this may mean there is a second, shallow reservoir buried about 656ft (200m) below the surface that is also active.
‘This indicates that the plumbing system is more complex and could be due to decreasing magma in a second, shallower reservoir,’ adds Ms Johnson.
In the future, the researchers hope that more measurements like these will build up a better picture of the volcano’s behaviour and improve eruption forecasting.
Co-author Dr Young Cheol Kim, of Penn State University, says: ‘Doing continuous monitoring allows us to understand the baseline activity and identify if things are changing.
‘And then if there is a need to warn people, we can do that in a timely manner.’