Pawan Dewangan-Senior Principal scientist, NIO, Sriram Gulapalli - Senior scientist, NIO. (Photo | Special arrangement)
Pawan Dewangan-Senior Principal scientist, NIO, Sriram Gulapalli - Senior scientist, NIO. (Photo | Special arrangement)

Indian scientists discover active submarine volcano in Andaman sea

The team is now gearing up for a mission involving the deployment of OBS in Andaman Sea to understand the genesis of earthquake swarms that have been occurring frequently in this region since 2004.

BENGALURU: Two Indian scientists from the National Institute of Oceanography (NIO), and their team have discovered an active submarine volcano (Crater Seamount) in the Andaman Sea, which has been at the epicentre of the seismic zone since it was first observed in 2007.

Crater Seamount has the potential to erupt at any time leading to earthquakes and even tsunamis in the Java-Sumatra region. The timing of the eruption however cannot be ascertained.

In 2018, Senior Scientist Sriram Gullapalli and Senior Principal Scientist Pawan Dewangan, both from the NIO, initially substantiated the existence of telltale signs of active gas venting above the shallow submarine volcano, which is located at 500m water depth in the Andaman-Nicobar Volcanic arc. They revisited their findings in 2021 and confirmed the submarine volcano in the Andaman-Nicobar Arc. Their findings were sent for peer review and the paper was published in the prestigious ‘Geo-Marine Letters’ - an international peer-reviewed journal in marine geology, geophysics, and geochemistry - in July this year.

Speaking exclusively to TNIE, Sriram said that for a long time, “Ocean scientists have been curious about the Nicobar underwater volcano area in the Andaman Sea. Our interest grew after the Tsunami-causing earthquake in 2004 and thereafter the increase in the number of earthquake swarms over the past two decades. In November 2007, some of us from the CSIR-NIO conducted a groundbreaking high-resolution multi-beam echo-sounding (MBES) survey over the earthquake swarm region, unveiling the presence of well-developed twin submarine volcanoes.

Generalized tectonic map of the Andaman-Nicobar-Sumatra subduction zone and tectonics features and yellow-filled red star denotes the cratered seamount.
Generalized tectonic map of the Andaman-Nicobar-Sumatra subduction zone and tectonics features and yellow-filled red star denotes the cratered seamount.

Subsequently, in 2014, we carried out an Ocean Bottom Seismometer (OBS) survey spanning four months, aimed at monitoring the volcanic arc. During this period, we detected earthquake swarms characterized by low-frequency and distinct hydro-acoustic phases, indicating the presence of sub-surface tectonic and magmatic influences that were associated with a shallow magma chamber,” said Sriram.

Building upon this research, Sriram and Dewangan along with some other scientists undertook two pioneering expeditions onboard the RV Sindhu Sadhana in 2018 and 2021.

“Our primary goals were to investigate the volcanic arc using MBES surveys and water column imaging (WCI) and to explore the geological significance of gas flares observed on the cratered seamount or the eye of the volcano. The 2018 expedition marked a pivotal moment in our understanding of the Nicobar volcanic arc,” he added.

Explaining in detail about the signature of the active volcano Sriram said that the “cutting-edge technology revealed the presence of two gas flares on the outer flanks of the cratered
seamount. The first, on the southeast flank, originated at a depth of 710 meters and reached heights of approximately 225 meters from the ocean surface. Similarly, the second flare on the northwest flank, originating at a depth of 400 meters and ascended to heights ranging from 150 to 100 meters. These gas flares provided compelling evidence of active volcanism in the region, prompting further investigations into its geophysical processes,” he explained.

In 2021, the expedition confirmed ongoing volcanic activity in the Nicobar submarine volcanic arc and made unexpected discoveries. “We aimed to remap a gas flare on the northwest flank and find anomalies. Surprisingly, we found a new gas flare to the south, originating at 380 meters depth and reaching 150 meters high. This discovery suggested varying venting activities at different seamount locations,” said the ocean scientist.

“The CSIR-NIO team is now gearing up for a crucial mission involving the deployment of OBS in the Andaman Sea to monitor the seismic activity of the Crater Seamount and understand the genesis of earthquake swarms that have been occurring frequently in this region since 2004,” said Dewangan. “The knowledge gained from this expedition holds the promise of bolstering our preparedness and resilience in the face of natural hazards, benefiting both scientific understanding and society as a whole,” he added.

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