Video Exhibits Pulsing and Curving Fault Habits

It took only one.3 seconds for the Sagaing Fault to open a gash in Earth’s floor and shift it by 2.5 meters in the course of the magnitude 7.7 Myanmar earthquake earlier this yr. When video surveillance some 120 kilometers south of the earthquake’s epicenter caught the second, the footage despatched a shock wave of pleasure via the worldwide seismology group.

At first, Jesse Kearse, a geophysicist at Kyoto University, was merely in awe of the tectonic forces, however as he rewatched the video, he quickly realized its scientific worth. “Of all the instrument records we have of earthquakes from the past 100 years, most are from far away,” he stated. This was the primary real-time commentary of a significant rupture near a fault.

Kearse and Yoshihiro Kaneko analyzed the video body by body utilizing a way referred to as pixel cross correlation. Their findings, revealed in The Seismic Record, revealed the pulse-like nature of main earthquake propagation and the curvature of fault slip.

How Earthquakes Move Along a Fault

Seismologists have lengthy understood {that a} fault doesn’t rupture abruptly. Instead, it experiences a touring, localized zone of slip, stated David Wald, a geophysicist on the U.S. Geological Survey in Golden, Colo., who was not concerned within the new analysis.

Wald’s work on the 1992 magnitude 7.2 Landers earthquake in California helped to determine that earthquakes propagate in pulses. But this work was “always a step removed from reality, modeling the rupture propagation process” versus watching it in actual time, he stated.

“Seeing is believing.”

“Seeing is believing,” Wald stated of the Myanmar footage. “We were all blown away by the video, which confirms how a short slip duration, large slip, and thus high slip velocity produce a large pulse of ground shaking.”

Analysis of the Myanmar earthquake video confirmed that the touring slip zone was solely a number of kilometers huge, although the earthquake finally ruptured a greater than 400-kilometer-long part of the fault. Pulse-like rupture is a extra environment friendly approach to transfer Earth’s huge crust, Kaneko famous. “This video provides the first visual confirmation of it occurring in real time.”

Although crumpled landscapes left by earthquakes have proven that seismic ruptures could cause everlasting offsets of many meters, till now it wasn’t clear whether or not that motion occurs inside 1 or 2 seconds. “The historic record shows the offset but not how quickly that happened,” Kearse stated. “It’s becoming clear that these pulse-like ground motions are really large amplitude, meters per second of ground velocity. For large buildings, that’s very difficult to engineer for.”

Curved Slip

The video evaluation was difficult as a result of floor shaking brought on the digital camera to tilt and wobble. But Kearse and Kaneko managed to isolate the fault movement by systematically analyzing stationary targets within the footage. To their shock, they watched the slip curve earlier than it settled into horizontal movement.

Geologists know that earthquakes go away curved scratch marks generally known as slickenlines on fault surfaces. In a previous study, Kearse and his colleagues described these grooves on uncovered surfaces of the Kekerengu Fault, considered one of a number of that ruptured in New Zealand’s 2016 magnitude 7.8 Kaikōura earthquake. When they fed these knowledge right into a mannequin, the staff discovered a hyperlink between the curvature of slickenlines and the course {that a} fault ruptured.

The evaluation of the Myanmar earthquake footage delivered real-time proof of this connection between slip curve and rupture course. “What our new study contributes is a quantitative analysis of both the speed and direction of the curved slip while the rupture is actively unfolding,” Kaneko stated.

The analysis “fortifies the slickenline story.”

The analysis “fortifies the slickenline story” and should assist seismologists higher anticipate the bottom shaking more likely to happen in future occasions, stated John Vidale, an Earth scientist on the University of Southern California. This understanding is especially vital for faults with the potential to rupture in huge earthquakes, together with California’s San Andreas Fault and New Zealand’s Alpine Fault. Such earthquakes would have an effect on main inhabitants facilities in another way, relying on the course wherein the earthquake traveled.

The Myanmar video additionally highlights the potential of autonomous cameras as instruments in seismology, based on Haiyang Kehoe, an Earth scientist who might be becoming a member of the University of Oregon in December. “The proliferation of home security systems and traffic cameras increases the likelihood that some portions of future earthquake ruptures will be recorded with a similar amount of clarity.”

For Laura Wallace, a geodetic scientist on the University of Texas and the GEOMAR Helmholtz Centre for Ocean Research Kiel in Germany, the work opens new potential for utilizing slickenlines from paleoearthquakes to analyze whether or not a specific fault tends to rupture in a single course or one other. “Such insights would provide important information for future seismic hazard forecasts.”

—Veronika Meduna (@veronikameduna.bsky.social), Science Writer

Citation: Meduna, V. (2025), Video exhibits pulsing and curving fault conduct, Eos, 106, https://doi.org/10.1029/2025EO250307. Published on 21 August 2025.

Text © 2025. The authors. CC BY-NC-ND 3.0
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