Reconstruction of record-breaking Myanmar earthquake confirms supershear event

The earthquake of magnitude 7.7 in Myanmar on March 28, 2025 caused widespread damage and more than 3,800 deaths, and also resulted in strong tremors and a collapse of the building in Bangkok, more than 1,000 km. Preliminary analysis shortly after the earthquake, said the unusually rapid speed of rupture, which is known as the sustainable rupture.

Now, a recent study by Felipe Vera by Gfz Helmholtz Center for Geosciences and Co-author confirms this discovery and combines several methods to shed light on the process of breaking this earthquake. According to the results, the Myanmar earthquake has shown the highest speed of rupture in the world in more than 20 years. The study is published in the journal The seismic file.

The comparison of optical satellite images before and after the earthquake allows a reconstruction of the ground distance from the soil on both sides of the fault, and similarly, the comparison of the images of satellite radar before and after allows a reconstruction of the vertical shift. These images show that the breakup occurred along the sagaing flaw over a distance of 500 kilometers, the west side moving north, and the east side moving south for a maximum gap of 5 meters near the epicenter, which was near the city of Mandalay.

Frederik Tilmann, one of the authors of the study and chief of the GFZ seismology section, says: “While satellite image analysis can give us a static vision of the effects of time tremor.”

In the vast majority of earthquakes, the rupture propagates at speeds of less than around 3.5 km / s (around 12,500 kilometers per hour), which corresponds to speeds a little less than the speed of seismic shear waves. And indeed, during the initial phase, the rupture spread at the same time to the north and south, far from the epicenter at usual speeds.

But after about 30 seconds, the rupture to the north stopped, and the rupture to the south accelerated at speeds of at least 5.3 km / s (almost 20,000 km / h). Seismologists call this a Supershear rupture, the seismic equivalent of the supersonic movement. This probably makes it the fastest recorded earthquake since 2002, when an earthquake in Alaska has reached similar speeds. The total duration of the rupture was approximately 80 seconds.

The Supershear propagation gives birth to a phenomenon called Mach’s cone; For the stations placed in its triangular outline on the surface, the seismic waves of the Supershear phase 40 to 50 seconds from the rupture of the rupture arrive at the same time. The study could demonstrate the existence of a Mach cone, which provides additional evidence of the Supershear propagation. This phenomenon could have improved long -term soil movement in Bangkok.

GFZ, in cooperation with the Myanmar Hydrology and Meteorology Department, operates a seismic station in Nay Pyi Taw, the capital of Myanmar, just 2 km from the fault. This station was active during the Myanmar earthquake and provided a remarkable and extremely rare quasi-faut recording of a Supershear rupture. The recordings were introduced into a recent publication by SSUNG-TING LAI and Co-Autors (Earthly system scientific data; in press). The station jumped 160 cm north when the rupture went nearby; This “jump” took less than 2 seconds.

It should be noted that sagain’s fault has been identified as subject to the sustainable rupture in previous studies due to the fact that it is the longest right slip flaw; Sliding defects are defects where both sides are mainly moving laterally compared to each other and the only ones capable of maintaining the Supershear rupture. It should also be noted that the slower slower part of the rupture occurred along parts of the fault which had broken during large earthquakes in 1946 and 1956, while the acceleration to Supershear occurred in the so -called sagain gap, which had not known very large earthquakes in more than a hundred years and was therefore presumed highly stressed.

Given the large size of the earthquake, the number and extent of the aftershocks were very low, which is another characteristic of the Supershear ruptures: due to the smooth propagation, the elastic constraint accumulated over the decades is rather relaxed, while in the earthquakes typical in the defect shift, often leaves behind the upper stress patches.