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Significant Earthquake in Myanmar Causes Widespread Devastation and Bangkok Building Collapse
A powerful earthquake originating in Myanmar on Friday has resulted in a significant loss of life, with over 1,600 fatalities reported, and widespread destruction of buildings and infrastructure. While Myanmar is located in a seismically active zone prone to earthquakes, the tremors were felt strongly in neighboring regions, including Thailand and China, which are not typically considered high-risk earthquake areas. The seismic event notably caused the collapse of an unfinished high-rise structure in Bangkok, the capital of Thailand, situated over 1,000 kilometers (621 miles) from the earthquake’s epicenter. This article explores the causes of this impactful earthquake and examines why its effects were felt so distantly, leading to building failure in Bangkok.
Understanding the Seismic Event’s Origins
The Earth’s crust is composed of tectonic plates, immense segments that are constantly in motion. These plates interact in various ways; some slide past each other, while others converge or diverge. This continuous movement is the fundamental cause of earthquakes and volcanic activity.
Myanmar’s location at the convergence of four major tectonic plates—the Eurasian, Indian, Sunda, and Burma microplate—positions it within a highly geologically dynamic region. The formation of the Himalayas is a direct consequence of the Indian plate colliding with the Eurasian plate. Similarly, the devastating 2004 tsunami was triggered by movement of the Indian plate beneath the Burma microplate.
Dr. Rebecca Bell, a tectonics expert from Imperial College London, explains that to accommodate this extensive tectonic motion, faults, or fractures in the Earth’s crust, develop, enabling plates to shift laterally. A prominent example is the Sagaing Fault, a major geological fracture stretching over 1,200 km (746 miles) north to south through Myanmar.
Initial data indicates Friday’s magnitude 7.7 earthquake was a “strike-slip” event, characterized by the horizontal movement of two crustal blocks past each other. This mechanism is consistent with the typical movement along the Sagaing Fault.
The buildup of friction as tectonic plates attempt to slide past each other can cause them to become locked. When this accumulated stress is abruptly released, it results in a sudden shift in the Earth’s crust, generating an earthquake.
Explaining the Earthquake’s Far-Reaching Effects
Earthquakes can originate deep within the Earth, as far as 700km (435 miles) below the surface. However, Friday’s earthquake was relatively shallow, originating only 10km beneath the surface. Shallow earthquakes generally produce more intense ground shaking at the surface.
Furthermore, the earthquake’s magnitude of 7.7 on the moment scale signifies a powerful event. The energy released by this earthquake exceeded that of the atomic bomb dropped on Hiroshima, according to the US Geological Survey, underscoring its immense strength.
Dr. Bell attributed the earthquake’s magnitude to the nature of the fault line. “The linearity of the fault means ruptures can extend across vast areas, and a larger rupture area corresponds to a more powerful earthquake,” she clarified.
She further noted, “This region has experienced six earthquakes of magnitude 7 or greater in the past century,” highlighting the area’s seismic history.
The fault’s linear nature also facilitates the propagation of energy along its length, extending 1200km southward towards Thailand, contributing to the distant reach of the earthquake’s impact.
Ground conditions also play a crucial role in how earthquake tremors are experienced. Bangkok is built on soft soil, which amplifies seismic waves. In such soil, these waves decelerate and increase in amplitude, resulting in more pronounced ground shaking.
Therefore, Bangkok’s geological composition exacerbated the intensity of the ground movement experienced during the Myanmar earthquake.
Bangkok Skyscraper Collapse: Investigating the Factors
While videos documented tall buildings in Bangkok swaying noticeably during the seismic event, with water surging out of rooftop pools, the unfinished headquarters of the Auditor-General’s office in Bangkok’s Chatuhak district appears to be the sole skyscraper that collapsed.
According to Dr. Christian Málaga-Chuquitaype, an earthquake engineering lecturer at Imperial College London, Bangkok lacked comprehensive earthquake-resistant building codes prior to 2009.
This absence of stringent early regulations implies that older buildings in Bangkok were potentially more vulnerable to seismic activity.
Earthquake-resistant construction can increase building costs, and Thailand, unlike Myanmar, experiences less frequent earthquakes. This difference in seismic frequency may have influenced building practices.
Professor Emily So, from the University of Cambridge, mentioned that retrofitting and strengthening older buildings is possible, as demonstrated in seismically active regions like California, western Canada, and New Zealand.
Construction Standards and Soil Conditions
Professor Amorn Pimarnmas, president of the Structural Engineers Association of Thailand, stated that while regulations for earthquake-proofing buildings existed in 43 provinces, it’s estimated that less than 10% of buildings actually adhere to these quake-resistant standards.
However, the collapsed building was recently constructed, subject to updated building codes. Thus, code deficiency alone may not fully explain the failure.
Dr. Pimarnmas suggested Bangkok’s soft soil may have contributed to the collapse by amplifying ground motions significantly.
He elaborated, “Other factors, such as the quality of materials (concrete and reinforcements) and potential irregularities in the structural system also warrant detailed investigation.”
Dr. Málaga-Chuquitaype, after reviewing video footage, noted the apparent use of “flat slab” construction, a method now discouraged in earthquake-prone zones.
“A ‘flat slab’ system involves floors resting directly on columns, omitting beams,” he explained.
“Picture a table supported only by legs, lacking horizontal supports beneath.”
“While this design offers economic and architectural advantages, it performs poorly during earthquakes, often failing suddenly and catastrophically.”
Seismic Vulnerability in Myanmar
Mandalay, Myanmar, situated closer to the earthquake’s origin, would have endured considerably more intense ground shaking than Bangkok.
Dr. Ian Watkinson, earth sciences lecturer at Royal Holloway University, suggested that despite Myanmar’s frequent earthquakes, earthquake-resistant construction is likely uncommon.
“Poverty, political instability, and other disasters like the 2004 Indian Ocean tsunami have diverted attention from the unpredictable risks of earthquakes,” he stated.
“Consequently, building codes may not be rigorously enforced, and construction may occur in areas susceptible to heightened seismic risk, such as floodplains and steep slopes.”
Parts of Mandalay and its buildings are located on the Ayerwaddy River floodplain, increasing vulnerability to liquefaction.
Liquefaction occurs in water-saturated soil when shaking causes it to lose strength and behave like a liquid. This elevates the risk of landslides and building collapses as the ground loses its load-bearing capacity.
Dr. So warned of the ongoing risk of aftershocks – subsequent tremors caused by energy redistribution in the earth’s crust – that could further damage structures near the fault line.
“Aftershocks are generally weaker than the main earthquake and decrease in frequency and magnitude over time,” she concluded.