Blogs

On 28th March 2025, a massive Mw 7.7 earthquake struck Mandalay, Burma, at 12:50 PM Myanmar time, causing widespread damage and casualties and raising concerns about seismic resilience in the region. This event serves as a stark reminder of the seismic vulnerability of Myanmar and neighbouring countries, including India. Given the region’s tectonic setting, understanding this earthquake is crucial for future risk mitigation.

Tectonic Background

The earthquake occurred as the result of strike-slip faulting between the Indian and Eurasia plates. Focal mechanism solutions indicate that slip occurred on either a north-striking, steeply-dipping, right-lateral fault or a west-striking, steeply-dipping, left-lateral fault. This focal mechanism is consistent with the earthquake potentially occurring on the right-lateral Sagaing Fault, which lies within the fault zone defining the plate boundary between the Indian and Sunda plates.

Although earthquakes are often plotted as single points on maps, events of this magnitude actually involve slip over a larger fault area. Strike-slip faults of this size are typically about 165 km in length and 20 km in width, indicating the significant extent of the rupture.

The region has experienced similar large strike-slip earthquakes in the past. Since 1900, six other Mw = 7 or larger earthquakes have occurred within 250 km of the event. The most recent was a Mw 7.0 earthquake in January 1990, which led to the collapse of 32 buildings. Additionally, a Mw 7.9 earthquake struck south of the current event in February 1912. Another major event, a Mw 7.7 earthquake in 1988, caused tens of fatalities within this broad zone of tectonic deformation.

Earthquake Characteristics

The earthquake had a Mw 7.7, making it one of the strongest in recent years in this region. The epicenter was located near Mandalay, Burma, at a depth of 10 km, indicating a shallow event, which generally amplifies ground shaking and causes extensive damage. The Peak Ground Acceleration (PGA) recorded for this earthquake was 0.68g, which contributed to severe shaking in Mandalay and surrounding regions. Preliminary data suggest that the event was caused by strike-slip motion along the Sagaing Fault, a well-known seismic source in Myanmar. While no major tsunami was reported, localized landslides and soil failures were triggered due to the intense shaking. A second strong aftershock of Mw 6.4 occurred 12 minutes after the initial quake, further compounding the damage and distress in the affected areas. Aftershocks are typically minor adjustments along the portion of a fault that slipped at the time of the initial earthquake.

Impact Assessment

The earthquake caused significant structural damage to buildings, roads, and bridges in Mandalay and surrounding areas.

Infrastructure Damage: Many reinforced concrete (RC) buildings with poor seismic design suffered severe damage, with some collapsing entirely. Historic structures and religious sites also sustained heavy losses.

Casualties & Injuries: Initial reports suggest 1012 fatalities and 2400 injuries, though the numbers may rise as rescue operations continue.

Seismic Vulnerability Highlighted: The disaster exposed poor construction practices and the dangers of soft soil amplification, which intensified ground shaking in certain areas.

Regional Effects: The tremors were felt in Bangladesh, Northeast (NE) India, and parts of China, raising concerns about cross-border seismic hazards.

Lessons for India and Seismic Risk in the Northeast

The entire NE Indian seismic belt shares similar geotectonic settings, making them highly vulnerable to earthquakes of this magnitude. This event underscores the urgent need for:

Improved seismic design codes for RC frame structures in hilly regions.

Comprehensive seismic vulnerability assessments, such as Rapid Visual Screening (RVS), to identify high-risk buildings.

Strengthening emergency response and preparedness to minimize casualties in future earthquakes.

Advanced numerical modelling for seismic risk assessment, focusing on soil-structure interaction and landslide-triggered failures.

Future Research Directions

As part of my research on Seismic Vulnerability Assessment of RC Frame Hilly Buildings, this event provides an opportunity to:

Analyze ground motion characteristics using numerical simulations.

Develop fragility curves for different building configurations to predict damage probabilities.

Assess landslide-triggered damages due to steep slopes and soil failures, crucial for hilly terrains in NE India.

Conclusion

The 2025 Mandalay earthquake reinforces the need for proactive seismic risk assessment and engineering solutions. By integrating numerical modelling, fragility analysis, and ground response studies, we can enhance resilience in earthquake-prone regions like Myanmar and NE India. Strengthening building codes, improving construction practices, and promoting disaster preparedness will be key to mitigating future risks.