Japan’s meteorological agency issued its first-ever “megaquake advisory” following a 7.1-magnitude earthquake off the country’s southern coast. The warning indicated an increased risk of a larger quake on the Nankai Trough, with the potential for temblors up to magnitude 9.1. The advisory highlighted the risk of strong shaking and a tsunami, urging residents to prepare for the possibility of a bigger earthquake over the next week.
The Nankai Trough is an underwater subduction zone where the Eurasian Plate collides with the Philippine Sea Plate, leading to stress build-up and the potential for megathrust earthquakes. Japanese scientists believe the fault is capable of producing an earthquake of up to magnitude 9.1, with the risk heightened by the recent earthquake and the segment’s proximity to a locked-up section that has been building stress since the 1940s.
While scientists cannot predict earthquakes, they are able to forecast times of heightened risk in areas with frequent shaking and good monitoring equipment, like Japan. The Nankai Trough has a history of producing large earthquakes every 100 to 150 years, with a recent study indicating a high chance of a megathrust earthquake in the next 30 years. The segment that recently experienced the magnitude-7.1 quake is in an area that shakes more frequently, providing some relief but highlighting concerns about the adjacent locked-up segment that could produce a significant earthquake.
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