A series of moderate earthquakes off the coast of Hokkaido, Japan’s northernmost island, has heightened concerns about the potential for a catastrophic megaquake.

According to the South China Morning Post, tremors ranging from magnitude 4.3 to 6.3 struck the region over a short period, with a notable magnitude 4.7 quake occurring just 16 minutes after a 6.3 tremor on Monday, June 3, 2025.

These seismic events, centered near the Chishima Trench, have prompted local authorities to urge residents to prepare for a worst-case scenario, despite scientists emphasizing that earthquakes remain unpredictable.

The recent seismic activity follows a broader pattern of concern in Japan, a nation situated along the volatile “Ring of Fire,” where 81% of the world’s largest earthquakes occur.

A five-year study by the Japan Agency for Marine-Earth Science and Technology, alongside researchers from Tohoku and Hokkaido Universities, highlighted the Chishima Trench as a potential source of a magnitude-8.8 earthquake due to accumulated seismic energy from tectonic plates that have been locked together since the 17th century.

The study suggests that a sudden release of this energy could unleash devastating consequences.

Japan’s history with megaquakes, such as the 2011 magnitude-9.0 Tōhoku earthquake that killed over 18,000 people and triggered the Fukushima nuclear disaster, underscores the gravity of these warnings.

While the Hokkaido tremors have not caused significant damage, with the U.S. Geological Survey reporting a low likelihood of casualties from the recent magnitude-6.1 quake on May 31, 2025, the government is taking proactive measures.

Local authorities are instructing residents to stockpile emergency supplies and identify evacuation routes, reflecting heightened vigilance.

The Japan Meteorological Agency (JMA) has also drawn attention to the Nankai Trough, another high-risk seismic zone, where a 70-80% probability of a magnitude 8-9 quake within the next 30 years has been estimated.

A government report from March 31, 2025, projected that a Nankai Trough megaquake could result in up to 298,000 deaths, 1.23 million evacuees, and economic damages of approximately US$1.8 trillion.

This follows a magnitude-7.1 quake in August 2024 off Kyushu, which prompted the JMA’s first-ever megaquake advisory.

While scientists caution that the recent Hokkaido tremors do not necessarily indicate an imminent megaquake, the region’s seismic history and ongoing tectonic strain keep Japan on edge.

The government’s focus on preparedness, coupled with public awareness campaigns, aims to mitigate risks in a country all too familiar with the destructive power of earthquakes.