1946 Sagaing earthquakes

Both the mainshock and aftershock occurred along the Sagaing Fault; a continental transform fault boundary that links the Andaman Spreading Center to the south and the Main Himalayan Thrust to the north.[3] It defines the boundary between the Burma Plate and Sunda Plate. The Sagaing Fault is the most active geological structure in the country and poses significant risks to major cities such as Yangon, Mandalay and Naypyidaw. Another major tectonic feature in Myanmar is the Sunda Megathrust that runs off the coast of Western Myanmar and the Kabaw Fault that traces the foothills of the Arakan Mountains and Indo-Burman Range.

The M8.0 mainshock ruptured along the Sagaing Segment of the Sagaing Fault with an epicenter south of the Singu Plateau at a depth of 15.0 kilometers.[4][5] It had a rupture length of approximately 185 kilometers. A second shock of magnitude 7.8 came three minutes later and ruptured north of the first event for a length of 155 kilometers, its hypocenter was at a depth of 15.0 kilometers.[4]

A pressure ridge along the Sagaing Fault, obstructed by vegetation, outside Mandalay. This section of the fault likely ruptured in the 1946 event.

Several major earthquakes have occurred along the Sagaing Fault close to the epicenter of the 1946 earthquakes:

• January 27, 1931: A magnitude 7.6 earthquake struck near the city of Myitkyina in Kachin State.[6]
• July 16, 1956: A magnitude 7.1 earthquake struck just outside Mandalay killing 38 people.[7]
• January 5, 1991: A magnitude 7.0 struck next to the Irrawaddy River.[8]
• June 15, 1992: A magnitude 6.3 occurred near Katha.[9]
• November 11, 2012: A magnitude 6.8 earthquake struck near Male, 120 kilometers north of Mandalay.[10][11] 26 lives were lost and went 12 missing.