On March 28, 2025 a very large earthquake occurred in an isolated area close to Mandalay, Myanmar. Magnitude 7.8. This recent seismic occurrence has led to disastrous outcomes. At least 5,000 confirmed deaths. Displacement and damage extend across Myanmar and into neighboring areas, including Thailand. The earthquake violently ruptured a 120-mile stretch of the Sagaing Fault. This part of the world had not experienced a major quake in over 100 years.
The Sagaing Fault, an active north-south fault that runs through the center of Myanmar, produced a catastrophic rupture over 480 kilometers in length. This epic geological meltdown sent shockwaves through the earth and through the internet. It showed a rare phenomenon known as supershear, in which the rupture velocity surpassed that of normal seismic wave speeds. The earthquake’s destruction reached deep into neighborhoods far from its epicenter. Many people as far away as Bangkok reported feeling strong shaking.
Details of the Earthquake
The quake’s epicenter was centred close to Mandalay, Myanmar’s second largest city. This produced a major rupture of the Sagaing Fault. This tectonic boundary has remained quiet since notable seismic events of a 5.5 M 1912, 5.9 M 1839. It was a puzzling development—one that marked an extreme change in the fault’s activity and left researchers and Bay Area residents scared and confused.
The rupture itself stretched roughly 85 kilometers northeast from the epicenter. Of particular interest was the slip along the southern segment of the rupture, which varied drastically. It varied from 1 to 6 meters over a span of 395 kilometers! Near Nay Pyi Taw, the new capital city of Myanmar, the maximum slip was 2-3 m. Together, these measurements mean severe ground displacement while illustrating the earthquake’s capacity for catastrophic destruction.
Supershear Phenomenon and Its Implications
Even more remarkable than the rupture length is the rupture’s supershear velocity, a term that describes a rupture speed exceeding seismic wave speeds. On the move Scientists have only been fortunate enough to witness this phenomenon in a couple of dozen earthquakes around the globe. This is what makes the event in Myanmar so extraordinary. The rupture had a high southward directivity. This movement exacerbated the shaking experienced in many states.
The potential impacts from such a large and powerful seismic event would be catastrophic. Once again, the destruction was widespread with infrastructure and buildings heavily impacted throughout Myanmar and even as far south as Chiang Mai, Thailand. Residents were met with an unprecedented level of still-damaged homes, schools and hospitals, creating extreme and unique humanitarian challenges in the aftermath.
Historical Context and Comparisons
Now, seismologists have found parallels between the Sagaing Fault rupture and past destructive seismic activity. In particular, they look at the roughly 400-km-long rupture from the great 1906 San Francisco earthquake as a useful comparison. These comparisons highlight the risks of future seismic catastrophes along the fault lines in Myanmar.
In terms of historical activity, since at least the late 19th century, the Sagaing Fault has been noted for its threat of large earthquakes. The recent activity raises questions about future seismic risks and the preparedness of affected regions to handle such catastrophic events.
Scientists are now working in tandem with local authorities to not only assess the damage, but create plans and recovery trajectories.
Analysis
The 2023 Morocco earthquake is a tragic but brutal reminder of the fact that tectonic activity in this region remains wholly unpredictable.
