Japan has issued its first-ever alert warning about the risk of a megaquake in the Nankai Trough following a magnitude 7.1 earthquake off the coast of Kyushu. The alert signifies an increased likelihood of a major earthquake, urging residents to stay vigilant and prepared for potential evacuations.
Key Takeaways
- Japan’s Meteorological Agency issued its first-ever alert for a potential Nankai Trough megaquake.
- The alert follows a magnitude 7.1 earthquake off the coast of Kyushu.
- Residents are urged to stay vigilant and prepared for potential evacuations.
The Initial Quake
On Thursday, a 7.1-magnitude earthquake struck off the coast of Miyazaki Prefecture on Kyushu, Japan’s southernmost main island. The quake occurred at a depth of 30 kilometers (18.6 miles), prompting a tsunami advisory. Although the expected tsunami height was only 1 meter (about 3.3 feet), the waves can grow exponentially very quickly.
The Alert System
The Japan Meteorological Agency (JMA) has a two-tier alert system for Nankai Trough megaquakes: an alert and a higher warning. The current alert is the lower level, urging people to be prepared for possible evacuations. A higher warning would necessitate immediate evacuation for those unable to do so quickly.
Historical Context
The Nankai Trough is a submarine trench that has historically been the source of devastating earthquakes. The most recent significant quake in this region occurred in December 1946, measuring between 8.1 and 8.4 on the moment magnitude scale. Such quakes typically occur every 100-150 years.
Government and Expert Reactions
Prime Minister Fumio Kishida and Chief Cabinet Secretary Yoshimasa Hayashi have urged the public to review their earthquake preparedness plans. Naoshi Hirata, an emeritus professor at the University of Tokyo, stated that the probability of a major earthquake has increased several times compared to usual.
Potential Impact
A major earthquake in the Nankai Trough could cause intense shaking from the Kanto region to Kyushu and generate high tsunami waves along the Pacific coast. Government estimates suggest that a Nankai Trough megaquake could result in up to 224,000 deaths, which could be reduced by 80% with timely evacuation.
Precautionary Measures
In response to the alert, Central Japan Railways has announced reduced train speeds between Mishima and Mikawa-Anjo stations, causing delays. Residents are advised to stay away from coastal areas and to be prepared for potential evacuations.
Conclusion
While the alert does not guarantee an imminent earthquake, it serves as a crucial reminder for residents to stay prepared. The JMA will continue to monitor the situation and update the public as necessary.
