Andaman Sea: India’s only active volcano, located on the uninhabited Barren Island in the Andaman Sea, erupted on September 20, in what experts described as a minor but scientifically significant episode. The eruption, marked by spurts of lava and volcanic ash, was triggered by a magnitude 4.2 earthquake that struck the region two days earlier.
Earthquake linked to volcanic activity
O.P. Mishra, Director of the National Centre for Seismology, explained that the eruption was a direct result of seismic disturbance. “It was the earthquake shaking intensity in the magma chamber of Barren volcano that erupted this month,” he said.
Barren Island, roughly circular with a diameter of 3.2 km, rises nearly 2 km above the sea floor, with an average height of 300 metres above mean sea level. The island lies close to the seismic fault line that slipped during the December 2004 Indian Ocean tsunami. Mishra said the quake made the magma chamber susceptible to “pre-mature magmatic eruption.”
History of episodic eruptions
The September 20 eruption is the fourth reported since 1991. The volcano last showed activity in 1991, 2004 and 2005, with each episode linked to seismic activity in the region. “This type of episodic volcanic eruption was witnessed in 1991, 2004, 2005, and now in 2025,” Mishra noted.
Despite the fiery visuals, there was no immediate risk to human settlements, as the nearest inhabited areas of the Andaman and Nicobar Islands are far from Barren Island. Indonesian settlements in the wider archipelago were also unaffected.
Why the region is vulnerable
The Andaman-Nicobar archipelago sits within a complex subduction zone, where the Indian plate pushes beneath the Sunda Plate. This tectonic environment makes the area prone to moderate and strong earthquakes, as well as frequent micro-seismic events.
“There are two magma-related lava volcanoes along the active West Andaman Fault. Though Barren Volcano has been active for years, eruptions are intermittent and sporadic, depending on whether the magma chambers 18–20 km below the surface are disturbed,” Mishra explained.
Scientific significance
Experts stress that such eruptions provide important data about the link between seismicity and volcanism in South Asia, a region where volcanic activity is relatively rare compared to the Pacific “Ring of Fire.”
Mishra added that lava and magma beneath Barren Island remain in constant motion, and seismic shocks often push hot material upwards through volcanic vents. “The hot materials are brought to the surface through cracks and fractures widened by the continuous seismically active cycle,” he said.
Dormant neighbour
The only other volcano in the region, Narcondam, remains dormant for now. However, scientists emphasise the need for ongoing monitoring of both volcanic and seismic activity in the Andaman and Nicobar region, given its strategic and ecological importance.
Conclusion
Though the latest eruption was minor and posed no immediate threat, it serves as a reminder of the geologically active and volatile nature of the Andaman region. The Barren Island volcano, silent for nearly two decades, has once again highlighted the delicate balance between seismic events and volcanic activity in South Asia.