Surface Rupture and Slip Distribution of the 2025 Mw 7.7 Mandalay Earthquake and Updated Length Scaling of Supershear Earthquakes
Journal
Seismological Research Letters
Journal Volume
97
Journal Issue
3
Start Page
1697
End Page
1720
ISSN
0895-0695
1938-2057
Date Issued
2026-04-21
Author(s)
Reitman, Nadine G.
Kuo, Yu-Ting
Hanagan, Catherine
Hatem, Alexandra E.
DuRoss, Christopher B.
Chen, Chun-Chi
Goldberg, Dara E.
Yin, Harriet Zoe
Briggs, Richard W.
Jobe, Jessica A. Thompson
Nicovich, Sylvia R.
Lynch, Emerson M.
Powell, Joseph
Barnhart, William D.
Schmitt, Robert
Abstract
The 2025 Mw 7.7 Mandalay, Burma (Myanmar), earthquake ruptured 475 km of the central Sagaing fault and is the longest continental strike-slip rupture on record. The observed rupture length is 1.6–4.7 times the value expected (100–300 km) from existing length–magnitude scaling relations for strike-slip earthquakes. The earthquake resulted from shallow dextral faulting and ruptured bilaterally with supershear speeds south of the epicenter, rupturing close to three major cities in Myanmar and exposing more than six million people to violent or extreme shaking. We report on the surface rupture character, length, and slip distribution based on subpixel correlation of Sentinel-2 (10 m) and Planet Dove (3 m) optical images and visual analysis of SkySat and WorldView (0.3–0.5 m) optical images. The earthquake had moderate surface slip (average = 3.3 m, maximum = 5.6 m, 25%–75%, range = 3.0– 4.0 m), narrow deformation zone width (1–10 pixels in subpixel correlation and ≤ 190 m for the detailed surface rupture mapping), and simple fault geometry (no stepovers or large changes in strike, 87% of the rupture that was mapped in detail is single stranded). We attribute the extreme length of the Mandalay earthquake to supershear rupture speed, simple fault geometry, narrow down-dip width, and moderate surface slip. Based on a compi-lation of 25 supershear strike-slip earthquakes (Mw 6.5–8.6; 1979–2025), we find that the rupture length of supershear earthquakes does not fit empirical scaling relationships for strike-slip earthquakes that predict length from magnitude. A length–magnitude scaling relationship based on supershear earthquakes has a best fit of log10 (surface rupture length) = 0.89 Mw – 4:44, indicating that supershear earthquakes tend to be longer than their subshear counterparts for any given magnitude and thus may expose a greater population to shaking.
Subjects
Seismological Research Letters
Mandalay
Myanmar
Earthquake effects
Fault slips
Geometry
Image analysis
Optical correlation
Pixels
Strike-slip faults
Myanmars
Rupture length
Seismological research letter
Slip distribution
Strike-slip earthquakes
Subpixel correlation
Supershear
Supershear earthquakes
Surface ruptures
Surface slips
earthquake epicenter
earthquake event
earthquake magnitude
earthquake rupture
fault zone
faulting
seismology
strike-slip fault
Geometrical optics
Publisher
Seismological Society of America (SSA)
Type
journal article