Meteorology Dept confirms Nicobar earthquake swarm poses no tsunami threat to Thailand
Meteorology Department says recent Nicobar quakes pose no risk to Thailand. Small quakes won't trigger tsunami. One-hour early warning system in place.
On July 4, 2025 at 12:33 PM, a 5.2-magnitude earthquake occurred in the Andaman Sea, north of Sumatra, Indonesia. According to the Department of Mineral Resources, there has been no reported impact on Thailand.
Between June 24 and July 4 (as of 1:00 PM), a total of 114 minor to light earthquakes (ranging from magnitude 3.4 to 4.9) were recorded in the eastern Andaman Sea, near India’s Nicobar Islands. These were identified as an earthquake swarm — a series of small quakes occurring over a short period — with no major shock involved.
The epicentre lies about 450 kilometres northwest of Muang District, Phang Nga Province, and around 100 kilometres from an undersea volcano.
Cause and Impact:
The quake swarm was caused by the horizontal movement of the Sumatra Fault in the Andaman Sea. Because the quakes were minor to light in magnitude, and occurred along a strike-slip fault line (horizontal movement), they did not displace water masses and therefore did not trigger a tsunami. This contrasts with the 2004 Indian Ocean tsunami, which was caused by a subduction zone earthquake and vertical fault movement.
Official Statement and Tsunami Criteria:
Nattawut Dandee, Deputy Director-General and spokesperson of the Thai Meteorological Department, confirmed that the recent quakes near the Nicobar Islands are not expected to cause a tsunami and pose no threat to Thailand.
He explained that tsunamis are usually triggered by:
- Undersea earthquakes
- Magnitude of 7.5 or higher
- Depth of less than 100 kilometres
- Occurrence along subduction zones or vertical fault movement
He added that Thailand has a tsunami early warning system capable of issuing alerts one hour in advance if a tsunami-generating earthquake occurs.
Members of the public can follow updates and earthquake activity through the official Earthquake Surveillance Division website: https://earthquake.tmd.go.th/ and the EarthquakeTMD-Thailand mobile app.
