Japan’s meteorological agency issued its first-ever “megaquake advisory” following a 7.1-magnitude earthquake off the country’s southern coast. The warning indicates an increased risk of a larger quake on the Nankai Trough, a subduction zone capable of producing temblors up to magnitude 9.1. The agency emphasized the heightened risk of strong shaking and a tsunami over the next week, urging residents to prepare.
Subduction zones like the Nankai Trough occur when tectonic plates collide, building stress that can result in powerful earthquakes. The Nankai Trough fault has multiple segments, with the potential to produce a magnitude 9.1 earthquake if the entire fault were to slip simultaneously. A megaquake in this area could result in intense shaking and a tsunami reaching nearly 100 feet in height.
The Nankai Trough has a history of large earthquakes occurring roughly every 100 to 150 years, with the most recent examples in 1944 and 1946. The recent magnitude-7.1 earthquake occurred in a segment that frequently shakes, potentially relieving stress. However, the concern lies in the earthquake’s proximity to a segment that has been accumulating stress since the 1940s.
While scientists cannot predict earthquakes, they can forecast times of heightened risk, particularly in areas like Japan with good monitoring equipment. The “megaquake advisory” serves as a forecast, not a prediction, highlighting the importance of preparedness and understanding the dynamics of subduction zone earthquakes to mitigate potential risks.
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