A relatively shallow right-lateral earthquake rocked Myanmar and other parts of southeast Asia, causing damage and death.
By Ross S. Stein, Temblor, Inc., and Shinji Toda, Tohoku University
Today, at 12:51 p.m. local time (6:21 a.m. GMT), a magnitude 7.7 earthquake struck near Mandalay, Myanmar (Figure 1). The focal mechanism reported by the U.S. Geological Survey indicates that this earthquake was strike-slip, which means that one side of the fault moved horizontally past the other. About 11 minutes later, a magnitude 6.4 event struck to the south. As of this writing, more than 150 deaths have been reported. A high-rise building under construction in neighboring Thailand collapsed.
The Mandalay earthquake appears to have struck on the right-lateral Sagaing fault, along a section with a slip rate of 24 millimeters per year based on GPS data (Tin et al., 2022). The region near this fault exhibits a high hazard in the Temblor model available in the Temblor mobile and web app. In 1946, a magnitude 7.7 earthquake struck just to the north of the inferred rupture of today’s quake.
We use Coulomb Stress calculations to determine how stress has been transferred as a result of today’s earthquake (Figure 2). We calculate that today’s earthquake brought portions of the Sagaing fault to the north and south the rupture closer to failure (Figure 2, red lobes). However, because the section to the north suffered an earthquake of the same magnitude 79 years ago, the more likely site for subsequent large earthquakes lies to the south, roughly centered on the city of Nay Pwi Taw. Our preliminary calculations use the USGS finite fault model for today’s magnitude 7.7 rupture.
References
Tin, T. Z. H., Nishimura, T., Hashimoto, M., Lindsey, E. O., Aung, L. T., Min, S. M., & Thant, M. (2022). Present-day crustal deformation and slip rate along the southern Sagaing fault in Myanmar by GNSS observation. Journal of Asian Earth Sciences, 228, 105125.
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