Curved Fault Slip Captured by CCTV Video During the 2025 Mw 7.7 Myanmar Earthquake

Abstract

Earthquake caught on cameraCCTV映像の解析で明らかになったミャンマー地震の断層すべり挙動 --湾曲したすべりとパルス的破壊の動態に関する新知見-- . 京都大学プレスリリース. 2025-07-24.On-fault geological observations from surface-breaking earthquakes typically contain curved slickenlines, suggesting fault slip is curved. However, slickenlines commonly record only a fraction of coseismic slip, making it difficult to reconstruct the full slip trajectory. Near-fault seismic records, though capable of capturing ground motions associated with rupture, are limited in their ability to constrain on-fault slip direction because they record motion on only one side of the fault. Here, we overcome these challenges by directly observing fault slip using video footage of the 2025 Mw 7.7 Myanmar, strike-slip earthquake. We use pixel cross correlation to track features in successive frames of the video, revealing a pulse of fault slip with a magnitude of 2.5 ± 0.5 m, a duration of 1.3 ± 0.2 s, and a peak velocity of 3.2 ± 1.0 m/s. The observed trajectory is notably curved and includes a transient (0.3 m) dip-slip component on a steeply dipping strike-slip fault. These observations are consistent with geological records of curved slickenlines, supporting mechanical models that link rupture propagation direction to near-surface slip curvature. Our results provide the first direct visual evidence of curved coseismic fault slip, bridging a critical gap among seismological observations, geological data, and theoretical models