INCOIS keeps watch on Barren Island volcano as it emits smoke

Tsunamis triggered by non-earthquake sources such as undersea landslides and volcanic eruptions can wash away communities within a few minutes, requiring constant vigil and faster response times

The volcano on the Barren Island of the Andaman & Nicobar Islands is being closely watched to check for signs of an eruption which could lead to a tsunami or a monstrous undersea landslide akin to what had happened in Indonesia in 2018. The monitoring is being carried out by the Indian National Centre for Ocean Information Services (INCOIS), which houses the Indian Tsunami Early Warning Centre (ITEWC) here.

“The volcano about 140 km northeast of Port Blair has been emitting smoke and is not capable of causing major destruction. Even if it does, there could be a localised tsunami but we are working on keeping a watch. We already have seven tide gauges in the Indian Ocean and there is a plan to put a seismic sensor and another tide gauge to catch any movement generated underwater,” informed senior scientist B. Ajay Kumar, in an exclusive interaction.

Recent tsunamis, including one in Tonga this year, have brought to the fore the challenge of tsunamis triggered by non-earthquake sources such as submarine landslides and volcanic eruptions which can wash away the regions near the source within a few minutes. This lack of awareness and preparedness by local communities and officials leading to slow responsiveness, needs to be addressed, said the scientist.

Scientists have calculated that it would take a magnitude of more than 6.5 on the Richter scale for a ‘tsunamigenic’ earthquake occuring in the Indian Ocean to hit the Indian coast, with travel time being 20 to 30 minutes to reach the A&N islands and two or three hours to hit the mainland. On India’s west coast, off the Arabian Sea, it could emerge from the Makran region and take two or three hours to reach the Gujarat coast. 

Tsunamis can travel from 800 kmph in the deep ocean and about 30 kmph near the shore, with wave heights ranging from less than a metre to nine metres when they reach the shoreline. This is the reason why ships in the deep seas may remain unaffected while the damage at the shore is more with amplifying energy, said Mr. Ajay Kumar. 

Though the devastating tsunami of December 2004 has faded away from public memory, ITEWC continues its round-the-clock vigil for unusual happenings on the sea to give advance warnings to 25 countries apart from India. Whenever an earthquake of more than 6.5 on the Richter scale occurs within the Indian Ocean (or above 8 on the Richter scale in other regions), timely and accurate tsunami bulletins are generated.

“We can estimate the expected wave heights and issue four threat levels corresponding to different public responses and mapped to NDMA (National Disaster Management Authority) guidelines about potential tsunamis, with confirmation and likely extent of inundation,” explained the scientist.