Japan is currently on alert for the possibility of a “megaquake,” which follows a recent 7.1-magnitude earthquake off its southern coast. This seismic activity raises concerns about a potentially devastating tsunami that could threaten thousands of lives.
The Japan Meteorological Agency (JMA) has released a map detailing regions that could be impacted by a tsunami resulting from a megaquake in the Nankai Trough. The map is color-coded to illustrate varying potential tsunami heights across the area.
In particular, some coastal zones could see waves reach up to 20 meters (approximately 65 feet). Areas in yellow might experience waves between 2 to 5 meters (about 6 to 16 feet), while regions marked in red could face waves of 10 to 20 meters (about 33 to 65 feet).
Regions from Shizuoka Prefecture to Miyazaki Prefecture are among the most vulnerable, possibly experiencing high seismic intensity. A tsunami could impact the broader Pacific coastline, extending from Kanto to Kyushu.
The recent 7.1 quake struck in the Hyuga-nada Sea near Kyushu, resulting in mostly minor injuries and no fatalities. In response, the JMA issued a caution-level warning about a potential megaquake for the first time.
If conditions worsen, an alert designation would prompt evacuation suggestions for those in danger zones. JMA officials noted that after a significant quake, the odds of an earthquake of magnitude 8 or higher increase substantially within the following week.
The Nankai Trough is a tectonic zone where the Philippine Sea Plate meets the Eurasian Plate, leading to significant earthquake activity due to the pressure build-up from the plates. Government officials are monitoring the situation closely, with Chief Cabinet Secretary Yoshimasa Hayashi advising citizens to prepare by securing their homes, identifying evacuation routes, and having communication plans ready.
Past assessments estimate that a megaquake could lead to around 224,000 fatalities, although prompt evacuations could significantly reduce this number by about 80%. Given Japan’s position on the Pacific Ring of Fire—where tectonic plates frequently interact—the country remains highly vulnerable to such natural disasters.