Security Footage Captures Rice Paddy Cracking During Kumamoto Earthquake

Security camera footage has captured the dramatic moment a massive crack split open a rice paddy in Yatsushiro, Kumamoto Prefecture, during the powerful Kumamoto earthquake on July 28.

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This is extremely rare and very useful for understanding the mechanism of earthquakes.

The earthquake, which registered a maximum intensity of 7 on the Japanese seismic scale, struck over 10 kilometers from Yatsushiro. The footage, recorded around 4:27 PM, shows the ground visibly shifting, exposing a fault line. The crack extends about 20 meters, and the ground on one side has risen approximately one meter higher than the other.

Mitsuaki Matsumura, the 45-year-old owner of the store where the camera was installed, described the intense shaking. "I was in a meeting inside the store when I felt the shaking. I’ve never experienced one so strong before," he said. After evacuating to the parking lot, he witnessed the large crack forming in the nearby rice paddy.

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I was in a meeting inside the store when I felt the shaking. I’ve never experienced one so strong before. We evacuated to the parking lot, and when I looked toward the rice paddy about 50 metres away, I saw the huge crack. The ground was uneven, and I could see a brown layer or earth.

Professor Shinji Toda, a seismology expert from Tohoku University, identified the phenomenon as a "fault scarp," formed when seismic activity causes the ground to uplift. He noted that the crack's location aligns with the direct extension of the Hinagu fault zone, believed to be the source of the earthquake. The appearance of the fault scarp seconds after the main seismic wave hit is attributed to the fault slip speed being slower than the seismic wave's propagation speed.

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The fact that the fault scarp appeared a few seconds after the main seismic wave hit is because the speed of the fault slip is slower than the speed at which the shaking propagates from the focus.

"Footage capturing the exact moment a fault scarp appears is extremely rare," Toda stated. "This footage holds high academic value for studying the mechanisms of fault ruptures caused by earthquakes." Damage from the earthquake was also reported in surrounding areas, including the collapse of a shrine gate and vertical displacement of a bridge.

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Footage capturing the exact moment a fault scarp appears is extremely rare. This footage holds high academic value for studying the mechanisms of fault ruptures caused by earthquakes.