Hi All,
The devastating earthquake that occurred on March 28 2025 at local time 11:50 am in Myanmar was of magnitude M7.7 and had a shallow focal depth of just 10 km. The epicentre was near the ancient city of Mandalay. As on date, over 2000 persons are dead and over 3900 injured in Myanmar.
Mandalay is the city where much of Amitav Ghosh's book,"The Glass Palace" which is an actual palace in the Mandalay Fort, is situated. Mandalay is a city steeped in history and mystique. I loved the city.
I had been to Myanmar a few months after the March 24 2011, 6.3 Mw Shan earthquake and some of the devastation was still visible. It had struck me even then how that country has been, and will be devastated again and again by earthquakes, given its history, geography and construction practices. It is a country of primarily solid, heavy, masonry construction. I had seen little evidence of even the most rudimentary seismic resistant features in their construction. People there seemed to be very fatalistic. “Whatever willbe, will be”.
As per USGS, “the March 28, 2025,M7.7 earthquake near Mandalay, Burma (Myanmar), occurred as the result of strike slip faulting between the India and Eurasia plates. The finite fault solution indicates the size of the March 28, 2025 event is about 200 km by 20km (length x width)… This region has experience similar large strike slip earthquakes, with six other magnitude 7 and larger earthquakes occurring with about 150 miles (250 km) of the March 28, 2025 earthquake since 1900. The most recent of these was a magnitude 7.0 earthquake in January 1990, which caused 32buildings to fall. A magnitude 7.9 earthquake occurred south of today’s earthquake in February 1912. Within this broad zone of tectonic deformation,other large earthquakes, including a magnitude 7.7 earthquake in 1988, have caused dozens of fatalities.”
Parts of Myanmar, and specifically the area around Mandalay, have been built and rebuilt many times after earthquakes. The Shwedagon Pagoda in Yangon, for example, (The Global Vipassana Pagoda in Mumbai is a replica of the Shwedagon Pagoda), said to be 2500 years old(!) has been rebuilt in recorded history numerous times following damage caused by earthquakes. The worst damage was caused by a 1768earthquake that brought down most of the top of the stupa...A moderate earthquake in October 1970 also caused significant damage. Serendipitously this pagoda does not seem to have undergone much damage in the 2025 earthquake but another large pagoda, Shwe Sar YanPagoda lost its topmost parts.
Another city frequently affected by earthquakes is the ancient city of Bagan. Bagan is one of the most beautiful historical sites you can visit. Between 1000 AD and 1250 AD, Bagan's rulers and its wealthy residents constructed over 10,000religious monuments (approximately 1000 stupas, 10,000 small temples and 3000monasteries) in an area of 104 km2 (40 sq mi)in the Bagan plains. Bagan is located in central Myanmar and has suffered from over 400 recorded earthquakes between1904 and 1975. An M7 earthquake occurred on 8 July 1975 near Mandalay, that damaged thousands of temples and pagodas severely and irreparably in Bagan. Today, only 2229 temples and pagodas of the over 10,000 built remain. Most recently, Bagan had sustained heavy damage in the 2016earthquake (M6.9). Bagan is a UNESCO Heritage Site spread with small and big pagodas and stupas (and nothing else) as far as the eyes can see. The March 2025 earthquake epicentre was only 10 miles from Sagaing, which is next to Bagan. I will not be surprised if once again, Bagan heritage has been badly destroyed in the earthquake.
The damage and collapse of buildings in Myanmar caused by the March 28 2025earthquake is available on social media and at many sites on the internet. But due to the damage and disruption of communication and transportation, the extent of damage and destruction in Myanmar is not fully known.
There are some interesting images of the damage in Myanmar including ground rupture and liquefaction on the NRSC, ISRO website.
One building of note in Mandalay to have collapsed is the 11-storey Sky Villa Condominium complex which had a rooftop bar and a modern gym. The failure of this multistorey building happened gradually, unlike the tower in Bangkok.
What has captured the imagination of structural engineers and laypersons worldwide is the collapse of a 30+storey tower, not yet fully completed, in Bangkok. The city of Bangkok is located more than 1,000km from the epicentre of Friday's earthquake. Here we were, shouting from the rooftops that tall buildings are not generally affected significantly by earthquakes; this collapse has collapsed this delusion that everyone has been carrying. This reminded me of the M8 1985 Mexico City earthquake in which buildings between 6 to 15 storeys (mostly flat slab and waffle slab buildings) collapsed/ were badly affected due to the soil effects (primarily amplification of ground motion) from an earthquake who’s epicentre was about 350 km away – Mexico city is famously sited on an old lakebed basin of volcanic ash and clay. Bangkok too is similarly situated on soft Bangkok clay, and even though it lies ata significant distance from any known active fault, due to Bangkok clay soils' proclivity to amplify certain ground motions, it is at risk of strong ground shaking from far-site earthquakes.
And yet it was one, just one, major building that collapsed (and connecting bridges of towers that got disconnected).The building pancaked, as it were, in a matter of seconds. The building displayed no ductile behaviour, the failure was brittle. I watched the failure in slow motion many times and what struck me was how the columns at the stilt level sheared off, like a clean knife-cut. Where was the reinforcement?
I think there is much to talk about this failure and I would like you to watch it carefully. Where did the failure initiate? What kind of failure was it? Was it a failure of the couplers? Or something else? Why did the core also come tumbling down?
Let’s do talk about it.
Thanks for reading!
Warmly,
Alpa Sheth
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