Seismologists reveal key rupture dynamics behind Myanmar quake

Seismologists reveal key rupture dynamics behind Myanmar quake
by Clarence Oxford
Los Angeles CA (SPX) Apr 10, 2025

The devastating magnitude 7.7 earthquake that struck Mandalay, Myanmar on March 28 caused catastrophic damage across the region and led to over 5,000 confirmed fatalities. Preliminary findings presented at the Seismological Society of America's Annual Meeting have begun to shed light on the fault rupture dynamics, seismic activity, and structural damage linked to the disaster.

Myanmar sits at the collision boundary of the Indian and Eurasian tectonic plates, a region known for complex geological activity. U.S. Geological Survey seismologist Susan Hough noted that the March event ruptured a 400-kilometer segment of the Sagaing fault, a primary strike-slip boundary that cuts through the heart of the country. This rupture represents one of the most extensive surface breaks documented globally.

USGS researcher Nadine Reitman explained that the affected portion of the Sagaing fault had remained relatively quiet since an 1839 magnitude 7 event, despite producing multiple magnitude 6+ quakes over the past century. She emphasized that the length of the March rupture makes it a standout event in modern seismic records.

Zhigang Peng of Georgia Institute of Technology reported that the earthquake rupture transitioned into "supershear" mode after a slow initial phase, a phenomenon where the rupture front travels faster than seismic shear waves. This behavior is consistent with other large strike-slip quakes. Peng also highlighted a notable uptick in seismic activity in neighboring regions such as Thailand and China's Yunnan and Guangdong provinces, attributing the increase to dynamic stress transfer from the mainshock.

Intense ground shaking was recorded well beyond the fault zone. Cities including Mandalay, Sagaing, Nay Pyi Taw, Bago, and parts of Shan State experienced significant shaking. According to Hough, the shaking was powerful enough to severely disrupt the Department of Meteorology and Hydrology in Nay Pyi Taw, which manages the national seismic network.

Shake intensity analyses shared by Chung-Han Chan of National Central University in Taiwan revealed that communities directly intersected by the fault likely endured shaking exceeding Modified Mercalli Intensity VIII. At this level, individuals may struggle to remain standing, heavy furniture can be displaced, and poorly designed structures are at risk of collapse.

Hiroshi Kawase from the General Building Research Corporation of Japan contributed insights from a long-term study of ground conditions in Sagaing and Yangon. His research helps estimate how local soil properties can amplify shaking during major seismic events.

Rapid damage assessments were aided by satellite technology. Xuechun Li of Johns Hopkins University demonstrated how remote imagery enabled detailed damage mapping in Mandalay within days of the quake. This capability could prove vital in accelerating disaster response.

A technological first also emerged from the event. Mikael Mazur of Nokia Bell Labs revealed that more than 100 seismic sensors were improvised from a submarine telecommunications cable network, allowing for real-time detection of the quake. This marks the debut of such a system for monitoring large magnitude earthquakes.