Marine expert warns of possible undersea volcanic eruption in Andaman Sea

In a Facebook post on Tuesday, Thon addressed growing concerns over frequent seismic activity in the area, which has sparked fears of a volcanic eruption beneath the Andaman Sea. He explained that tsunamis are typically caused by undersea earthquakes or volcanic explosions.

He clarified that the recent earthquakes in Myanmar are unlikely to trigger a tsunami as they occurred inland. However, Thailand could still experience direct effects from such quakes.

“Tsunamis in the Gulf of Thailand are highly unlikely, and even if they occur, they would be small and detected well in advance due to the distance from major seismic and volcanic zones like Indonesia and the Philippines,” he wrote.

Thon said there are two potential tsunami-trigger zones — one in Indonesia and the other along the Andaman and Nicobar Islands in India.

“The only volcanic island in this area is Barren Island, which remains active. However, recent tremors have not originated from there, but from further south along the same volcanic belt – one that lies entirely underwater,” he explained.

He added that this section of the sea is over 2,000 metres deep, with Barren Island being the only volcano in the belt that has erupted above sea level – most recently in 2022.

“An eruption from an underwater volcano in the same chain is certainly possible, but no one can say when. The recent frequent quakes in the area – especially those above magnitude 4 – may indicate magma movement, but it doesn’t necessarily mean an eruption is imminent,” Thon said.

He cited the eruption of Hunga Tonga–Hunga Haʻapai in 2022 as an example of a volcanic eruption that caused a tsunami. That eruption generated waves as high as 20 metres, and in some areas even higher, though casualties were limited due to its remote location in the Pacific Ocean.

Referring to data from Thailand’s Earthquake Observation Division, Thon noted that the current cluster of seismic activity lies 470–480 kilometres off the coast of Phang Nga. If a volcanic eruption were to occur there, a tsunami could form due to the deep water and the resulting large volume of displaced seawater.

This location is closer to Thailand than the epicentre of the 2004 earthquake and tsunami, meaning any resulting waves could reach the coast more quickly than in that past event – which took around two hours. The different epicentre and mechanism could also result in different wave patterns, affecting areas that were previously less impacted.

Thon encouraged tsunami evacuation drills, calling them a positive step, but urged the public not to panic. “No one can predict with certainty whether a disaster will occur. In Japan, for example, warnings have been issued for months without any major event materialising,” he said.

Still, he advised families to have emergency plans in place, know the nearest evacuation routes, and practise what to do in case of an emergency.

Reflecting on past tsunamis, he said that even three-storey buildings might not provide enough safety. Drawing from Tonga’s example, he recommended seeking shelter in buildings with at least 7–8 storeys, or following designated evacuation routes if such buildings are unavailable. 

He also urged schools to clearly communicate emergency procedures to parents to avoid traffic congestion during evacuations.

Finally, Thon warned against falling for unfounded rumours spread by individuals without proper scientific credentials.

“Don’t let baseless rumours spread fear. Rely on verified information from experts and official agencies with proper backgrounds in this field. Expertise takes years of study and research – it’s not something granted overnight,” he wrote.