Dramatic CCTV video of fault slip throughout a big earthquake in Myanmar thrilled each scientists and informal observers when it was posted to YouTube. But it was on his fifth or sixth viewing, stated geophysicist Jesse Kearse, that he noticed one thing much more thrilling.
When Kearse and his colleague Yoshihiro Kaneko at Kyoto University analyzed the video extra rigorously, they concluded that it had captured the primary direct visible proof of curved fault slip.
Earthquake geologists typically observe curved slickenlines, the scrape marks created by blocks of rock transferring past one another throughout faulting. But till now there was no visible proof of the curved slip that may create these slickenlines.
The video affirmation of curved fault slip might help researchers create higher dynamic models of how faults rupture, Kearse and Kaneko conclude of their paper published in The Seismic Record.
The video comes from a CCTV safety digicam recording alongside the hint of Myanmar’s Sagaing Fault, which ruptured 28 March in a magnitude 7.7 earthquake. The digicam was positioned about 20 meters to the east of the fault and was 120 kilometers away from the earthquake’s hypocenter.
The ensuing video is astonishing. A fault in movement as by no means seen earlier than—shaking adopted by a visual northward slide of the land on the western facet of the fault.
“I noticed this on YouTube an hour or two after it was uploaded, and it despatched chills down my backbone immediately,” Kearse recalled. “It exhibits one thing that I believe each earthquake scientist has been determined to see, and it was good there, so very thrilling.”
Watching it again and again, he observed one thing else.
“Instead of issues transferring straight throughout the video display screen, they moved alongside a curved path that has a convexity downwards, which immediately began bells ringing in my head,” Kearse stated, “as a result of a few of my earlier analysis has been particularly on curvature of fault slip, however from the geological document.”
Kearse had studied curved slickenlines related to different earthquakes, such because the 2016 magnitude 7.8 Kaikoura earthquake in New Zealand, and their implications for understanding how faults rupture.
With the Myanmar video, “we set about to quantify the motion a bit extra rigorously, to extract goal quantitative data from the video somewhat than simply pointing at it to say, look, it is curved,” he stated.
The researchers determined to trace the motion of objects within the video by pixel cross correlation, body by body. The evaluation helped them measure the speed and route of fault movement in the course of the earthquake.
They conclude that the fault slipped 2.5 meters for roughly 1.3 seconds, at a peak velocity of about 3.2 meters per second. This exhibits that the earthquake was pulse-like, which is a serious discovery and confirms earlier inferences comprised of seismic waveforms of other earthquakes. In addition, a lot of the fault movement is strike-slip, with a short dip-slip part.
The slip curves quickly at first, because it accelerates to high velocity, then stays linear because the slip slows down, the researchers discovered.
The sample suits with what earthquake scientists had beforehand proposed about slip curvature, which could happen partly as a result of stresses on the fault close to the bottom floor are comparatively low.
“The dynamic stresses of the earthquake because it’s approaching and begins to rupture the fault close to the floor floor are capable of induce an obliquity to the fault motion,” stated Kearse.
“These transient stresses push the fault off its supposed course initially, after which it catches itself and does what it is presupposed to do, after that.”
The researchers beforehand concluded that the kind of slip curvature—whether or not it curves in a single route, or within the different—relies on the route that the rupture travels, and is per the north to south rupture of the Myanmar earthquake.
This implies that slickenlines can document the dynamics of past earthquakes, which could be helpful for understanding future seismic dangers.
More data:
Jesse Kearse et al, Curved Fault Slip Captured by CCTV Video During the 2025 Mw 7.7 Myanmar Earthquake, The Seismic Record (2025). DOI: 10.1785/0320250024
Provided by
Seismological Society of America
Citation:
Curved fault slip captured on CCTV throughout Myanmar earthquake ( 21)
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