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India’s only active volcano, located in a remote and uninhabited Barren Island on the Andaman Sea, erupted on September 20 after an earthquake struck the region two days before the eruption.
While the volcano itself was not harmful, with no reported destruction or deaths, the island lies on a fault that moved, resulting in the tsunami of December 2004.
O P Mishra, director, National Centre for Seismology, told TOI that the fault’s coordinates align with the same latitude as the Barren Island volcano and are near the longitude of the quake that made the magma chamber apt for a “pre-mature magmatic eruption.”
Mishra stated that it was the “earthquake shaking intensity” within the magma chamber of the Barren Island volcano that triggered this month’s eruption. Barren Island itself is roughly circular, with a diameter of about 3.2 kilometres. The volcano rises nearly 2 kilometres from the sea floor, with an average elevation of 300 meters above mean sea level.
“Andaman-Nicobar Island is located in the subduction complex consisting of the down going Indian plate intruding to the mantle of the overriding Sunda Plate where continuous earthquakes of moderate to strong strengths used to occur besides the micro seismicity in the area,” he said.
The Barren Island eruption was the fourth one since 1991. The volcano in the region has been active for years, but eruptions have been sporadic, causing no immediate danger to nearby areas.
Lava and magmatic eruptions occur periodically when seismic energy from moderate to strong earthquakes disturbs the magma chamber, causing lava to rise to the surface through volcanic vents.