A powerful earthquake in northern Japan on December 8 prompted the country's government to issue a warning for the first time this year that the risk of a super earthquake next week is increasing.
Scientists are still unable to determine whether or not that super earthquake will occur, or when it will occur. However, the likelihood of an earthquake of 8 degrees richter or more next week has increased to about 1%. The number is small, but it is a significant increase compared to the normal probability.
The Japanese government uses the term super earthquake to refer to earthquakes with strong gusts above 8 degrees richter. To make it easier to imagine, an 8-degree richter earthquake is approximately 32 times stronger than a 7-degree richter earthquake.
That is why even 1%, Japanese authorities still consider it a serious risk.
After any earthquake of 7 degrees richter or more, Japanese scientists review historical data. This was triggered on December 8 when a 7.6-magnitude earthquake rocked northern Aomori Province.
The government issued a warning for the risk of an higher than normal 8-degree richter, according to Professor Fumiaki Tomita of the Institute for Natural Sciences Research, Tohoku University.
The Japan Meteorological Agency said that based on global historical data, the probability of an 8-degree richter earthquake in the next 7 days is currently 1/100. Japan previously issued its first super earthquake warning in 2024; the warning expired after seven days without a stronger earthquake.
The Japanese government mentioned the 2011 series of earthquakes to explain this warning. Before the 9.1-magnitude earthquake on March 11, 2011 that caused a Tsunami and killed more than 19,000 people, a smaller earthquake had occurred just two days earlier.
Professor Takuya Nishimura of Kyoto University said that although the 1% is low, it is still 10 times higher than the average risk of an 8-degree earthquake in the area. The warning area stretches from northern Japan to near Tokyo.
Japan is located on the Pacific Ring of Fire, the region with the most active faulty areas in the world. The country records about 1,500 earthquakes per year, an average of 3 per day, according to the University of Tokyo.
Japan's history has recorded many super earthquakes, including the 2011 disaster, the strongest in the country's history. In 2003, an 8-magnitude richteric earthquake off the coast of Hokkaido caused widespread power outages.
" Concerns about major earthquakes in Japan are always a reality," said Professor Meghan S. Miller, School of Earth Sciences Research, Australian National University.
Japan's super earthquake warning system has been deployed since 2022. Although it is impossible to predict the exact time, location or intensity of the earthquake, Japan still has one of the most advanced early warning systems in the world, according to Professor Miller.
The Japanese government operates hundreds of seismic measuring devices on land and underwater. When an earthquake occurs, the system will detect the first seismic wave in just a few seconds and send an immediate warning.
If the intensity of the shaking reaches level 3 or higher on the Japanese 10-level scale, the Japan Meteorological Agency will issue a report within 90 seconds.
