Analysis Quake Risk Lurking Under Bangkok: Fault Lines Spell Trouble

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Bangkok's unique geography makes it susceptible to earthquakes, despite Thailand's low overall risk of tremors, warns Prof Pennung Warnitchai from the Asian Institute of Technology.

 

Speaking at the Bangkok Post Knowledge Forum, he shed light on how the city’s soft soil amplifies seismic waves, posing a potential hazard for high-rise buildings even from distant quakes.

 

Prof Pennung illustrated the impact of these features by referencing the earthquake felt in Bangkok on March 28, which originated from Myanmar's Sagaing Fault.

 

"The city's soft soil and basin-like terrain slow and amplify seismic waves, resulting in long-period ground motion," he said. This soil composition can magnify ground motion by up to four times, significantly affecting tall structures.

 

With the possibility of local and regional earthquakes, Prof Pennung described three hypothetical quake scenarios that could threaten Bangkok.

 

These include a 7.5-magnitude quake along the Kanchanaburi Fault, an 8.0-magnitude quake along the Sagaing Fault in Myanmar, and a rare 8.5-9.0 magnitude quake from the Andaman Sea fault.

 

Despite the statistical improbability of these occurrences, with a mere 10% chance of happening in a lifetime, they highlight a non-zero risk.

 

In response, since 2007, Bangkok has imposed building regulations requiring new constructions to adhere to earthquake-resistant standards.

 

The city is divided into ten zones, each with tailored building codes to manage local risk levels. Additionally, Bangkok employs five seismic monitoring stations that gather data to support these safety measures.

 

Most damage reported in the capital has been minor, affecting non-structural aspects of buildings rather than causing structural failures. However, the collapse of the State Audit Office building in Chatuchak after a recent tremor suggests lapses.

 

Prof Pennung, part of the investigation committee, indicated the building's unstable state contributed to its downfall, pending further inquiry into potential factors like corruption, poor materials, or design flaws.

 

This analysis underscores Bangkok's vulnerability while reminding that robust building practices and monitoring are crucial in mitigating seismic risk.

 

  Adapted by ASEAN Now from Bangkok Post 2025-05-16