AFTER a 7.8 magnitude earthquake struck off Philippines island of Mindanao early this morning (June 8) killing 15 people and injuring over 100 a noted Thai academic warned that while short waves in the Philippines quake caused damage to low-rise buildings, Bangkok’s soft soil poses a risk of the metropolis being rocked by long waves from distant fault lines, potentially causing tall buildings to collapse, according to Naewna newspaper and reports by agencies published by CNA.
Prof. Dr. Amorn Pimanamas, president of the Structural Engineers Association of Thailand and a professor at the Faculty of Engineering, Kasetsart University, analysed the impact of the Philippines earthquake that sparked tsunami warnings across the region with there also being a series of powerful aftershocks for about two hours after the first one.
He pointed out that the earthquake off the Philippines was very strong, given the Philippines’ location on the Ring of Fire, an area of constant tectonic activity. Furthermore, the epicentre was only about 20-30 kilometres from General Santos City, which from an engineering perspective, is considered a “near-field earthquake”.
This type of earthquake generates high-frequency seismic waves, which significantly impact small and low-rise buildings, especially those less than five stories high. This is evident in the numerous low-rise buildings that collapsed this morning.
He explained that the characteristics of the Philippines earthquake are fundamentally different from the 7.7 earthquake centred in Myanmar city of Mandalay that shook Bangkok on March 28 last year leading to the State Audit Building collapsing as this originated from the Sagaing fault line in Myanmar and a group of faults in Kanchanaburi province. These fault lines are hundreds to thousands of kilometres away from Bangkok, classifying this as “far-field earthquake.”
“Seismic waves reaching Bangkok from afar transform into ‘long-period waves’. These waves don’t affect low-rise buildings but have much greater destructive power and damage tall buildings because their frequency aligns with the natural shaking period of high-rise buildings,’ Prof. Dr. Amorn said.
He emphasised with concern that Bangkok is currently not considered safe from earthquakes, especially distant ones. This is due to Thai capital’s physical topography, situated on soft clay, which has the unique property of amplifying earthquake waves many times over when they arrive. This factor poses a direct threat to the structures of high-rise buildings in a large city.
To prevent future losses, he proposed three urgent policy recommendations for Bangkok Metropolitan Administration and related agencies to consider as follows:
– Establish a risk database: A systematic survey of building structures and a risk database of all buildings in Bangkok should be urgently compiled;
– Improve the structures of older buildings: Consider implementing measures or regulations to strengthen the structures of older buildings constructed before the earthquake-resistant building code came into effect.
– Install an early warning system: An earthquake sensor and early warning system should be installed in important buildings, public buildings, and high-rise buildings with high occupancy rates to allow for timely evacuation in case of emergencies.
CAPTIONS:
Top and Front Page – Prof. Dr. Amorn Pimanamas next to an image of low-rise buildings that collapsed in the Philippines during this morning’s earthquake. Photo – Naewna
Insert – Police gather in front of a collapsed Jollibee fast food restaurant after a 7.8 magnitude earthquake in General Santos City on June 8, 2026. Photo – Edwin Espejo/AFP/Getty Images and published by CNN
Watch video of a building collapsing at General Santos City in the Philippines shared by Weather Monitor on X.com:
https://x.com/WeatherMonitors/status/2063880391464022208/video/1
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