Expert analyses tsunami risk after over 15 earthquakes in the Andaman Sea

Prof Santi Pailoplee, a geology expert from the Department of Geology, Faculty of Science at Chulalongkorn University and owner of the "Mitrearth" Facebook page, has posted an analysis regarding the recent series of moderate earthquakes (ranging from 3.x to 5.x magnitude) in the Andaman Sea. 

He provided insights into the potential risks, including the likelihood of a tsunami, following over 15 seismic events off Thailand's southern coast.

On June 25, 2025, Santi shared his scientific observations as follows:

• Earthquake Epicentre Location: The quakes have occurred in a cluster near an area reported to be a submerged volcano (see attached images with red circles marking the locations). If the earthquakes are caused by magma pushing up rocks, they are typically not large quakes. However, they could be a warning sign of volcanic activity. If an underwater eruption were to happen in this location, it could potentially generate a tsunami impacting Thailand’s Andaman coast.
• Past Earthquake Activity: Santi referred to a black and white map showing that a similar cluster of earthquakes occurred in this area in 2005, which did not result in any significant events for Thailand.
• Historical Earthquake Data: The same map also indicates that the area has experienced larger earthquakes in the past, including a 7.5 magnitude earthquake in 1847 and a 7.9 magnitude earthquake in 1881. While large earthquakes have occurred, they were not capable of triggering tsunamis due to the fault lines being part of a horizontal strike-slip system linked to the Sumatra Fault on the nearby island of Sumatra, which is typically less likely to generate tsunamis.

Conclusion:

Based on historical data, Santi advised the public on Thailand’s Andaman coast to monitor the situation closely. The possibilities remain:

• Nothing significant happens—just a series of moderate quakes that will pass.
• An underwater volcanic eruption could occur, potentially causing tsunami waves to hit Thailand’s Andaman coast.
• Although unlikely, a large earthquake in the area could occur, but it is unlikely to generate a tsunami due to the fault's horizontal slip motion, which typically does not displace enough water to create one.

Meanwhile, the Department of Disaster Prevention and Mitigation will conduct a simulated tsunami evacuation drill in six provinces along the Andaman Sea coast. The drill will take place on Friday, June 27, 2025, at 2.30pm.

During the drill, a tsunami warning will be issued through local alarm towers, with the following alerts:

M2 (Earthquake in the Sea Warning)

“Attention, attention, an earthquake has occurred in the sea. A tsunami may follow. Please evacuate the beach area and move to higher ground immediately.”

M3 (Tsunami Warning)

“Attention, attention, a tsunami is now occurring. Please evacuate the beach area and move to higher ground immediately.”

The drill will be carried out in the following locations across the six provinces:

Ranong: Ban Bang Ben and Ban Ao Koei, Muang Luang Subdistrict, Kapoe District

Phang Nga: Ban Nam Khem, Ban Bang Sak Nuea, and Ban Bang Sak Tai, Bang Muang Subdistrict, Takua Pa District

Krabi: Nopparat Thara Beach, Ao Nang Subdistrict, Mueang Krabi District

Trang: Hat Sai Thong Beach, Koh Sukon Subdistrict, Palian District

Satun: Tanyong Po Subdistrict, Mueang Satun District

Phuket: Kamala Beach, Kathu District

Residents in the affected areas are requested not to panic and to participate in the drill as scheduled. This exercise is aimed at enhancing disaster preparedness and ensuring an effective response in the event of a real tsunami threat.