Japan is highly susceptible to seismic events, particularly along the Nankai Trough, where there is an 80 percent likelihood of experiencing a magnitude 8 to 9 earthquake.

In a worst-case scenario, a magnitude 9 earthquake could result in approximately 1.23 million evacuees, which represents about 10 percent of Japan's population.

The Nankai Trough, a 900-kilometer-long seismic zone off Japan's southwest Pacific coast, is characterized by the subduction of the Philippine Sea Plate beneath the Eurasian Plate, leading to accumulating tectonic strain.

The potential human toll from such an earthquake could be catastrophic, with estimates suggesting up to 298,000 fatalities, particularly if the quake occurs at night during winter.

The economic impact of a megaquake is projected to reach up to $1.81 trillion, nearly half of Japan's total GDP, reflecting a significant increase from previous estimates.

The disaster's human toll could vary significantly based on evacuation rates, which are currently estimated at only 20%, underscoring the importance of effective evacuation strategies.

The anticipated seismic event is expected to trigger massive tsunamis, building collapses, and long-term infrastructure destruction, further complicating recovery efforts.

To enhance preparedness for future megaquakes, Japan plans to establish a new agency dedicated to disaster prevention by 2026.

In response to the ongoing seismic risks, Japan is revising its national disaster prevention framework and implementing a national resilience plan.

Experts estimate a 75% to 82% chance of an 8 or 9 magnitude earthquake occurring in the Nankai Trough within the next 30 years, with the likelihood increasing by about 1% each year.

Japan experiences around 1,500 earthquakes annually, though most are of low magnitude; however, a recent 7.6 magnitude tremor in January 2024 resulted in over 500 deaths.

In 2024, Japan issued its first megaquake advisory following a 7.1 magnitude quake near Kyushu, highlighting the heightened risk of a significant seismic event.