Mexico’s deadly 1982 volcano shows renewed activity

After more than 40 years of relative silence, Mexico’s El Chichón — also known as Chichonal — is displaying renewed signs of activity, prompting close scientific monitoring.

Researchers from the National Autonomous University of Mexico (UNAM) recorded rising temperatures, increased gas emissions and unusual sulfur formations inside the volcano between June and December 2025, News.Az reports, citing Daily Mail.

El Chichón last erupted in 1982 in one of Mexico’s deadliest volcanic disasters, killing at least 2,000 people and devastating surrounding communities.

During recent monitoring, scientists observed elevated heat levels, changes in the crater lake’s chemistry and the release of gases including hydrogen sulfide (H₂S) and carbon dioxide (CO₂), which can be dangerous in high concentrations. They also documented rare hollow sulfur spheres forming in liquid sulfur pools within the crater.

Despite these striking developments, researchers say there is no evidence of magma rising beneath the volcano. Experts stress that the activity appears to be hydrothermal in nature and does not signal an imminent eruption.

The findings are based on fieldwork and remote monitoring conducted by UNAM’s Institute of Geophysics, which has studied the volcano’s internal processes for years. Scientists noted that the normally green crater lake had turned grayish, suggesting increased sulfate and silica levels.

Thermal readings revealed temperatures at the lakebed and surrounding crater floor exceeding typical background levels. Researchers also detected fluctuating chloride concentrations and shifting gas-water interactions — indicators that hot fluids are circulating underground.

Gas sampling showed hydrogen sulfide and carbon dioxide accumulating near the crater, posing potential risks if concentrated in enclosed or low-lying areas. However, volcanologists emphasize that such emissions are common in active hydrothermal systems and do not necessarily point to an eruption.

Volcanologist Patricia Jácome Paz said the unusual activity is most likely caused by superheated groundwater interacting with hot rock rather than molten magma rising toward the surface.

“The observed behavior is consistent with hydrothermal processes or minor steam-driven explosions,” she said in a recent lecture on the findings.

Seismic data from the area show only low levels of earthquake activity, further suggesting magma is not currently moving beneath the volcano.

Although access to the site has been restricted since 1982, El Chichón remains a crucial research location for studying how volcanoes evolve long after major eruptions. Its crater lake and sulfur deposits provide insights into how heat and fluids reshape volcanic systems over time.

The memory of the 1982 disaster still looms large in southern Mexico. Beginning on March 28 that year, a series of powerful eruptions sent ash high into the atmosphere and unleashed deadly pyroclastic flows, destroying entire villages and burying farmland. The disaster caused widespread economic and environmental damage across the region.

Scientists say the current activity differs significantly from the conditions that preceded the 1982 eruption. Still, they caution that volcanoes can remain dynamic for decades or even centuries after major events.

To closely track changes, researchers are using drones, satellite imaging and on-site instruments to monitor thermal anomalies, gas plumes and ground deformation. Continuous observation is essential, they say, as volcanic systems can shift rapidly and early detection is critical for public safety.

For now, experts stress there is no reason for public alarm. However, the renewed activity at El Chichón serves as a reminder that dormant volcanoes are rarely entirely inactive, and that processes deep underground can continue long after surface eruptions have ceased.

News.Az 

By Nijat Babayev