After a magnitude 7.5 earthquake struck north-eastern Japan, authorities have emphasized the potential for a future megaquake, commonly referred to as the 'big one'. This term represents a significant seismic event believed to occur approximately once every century.
In September, Japan's earthquake investigation panel indicated a 60-90% probability that such a quake would occur in the Nankai Trough, a highly active seismic zone along Japan's Pacific coast, within the next 30 years.
Given past warnings that a megaquake could prompt a tsunami exceeding 20 meters, potentially affecting Tokyo and causing hundreds of thousands of fatalities, preparedness has become crucial.
Officials advised residents in seven prefectures from Hokkaido to Chiba to remain alert for potential quakes. Although there was no evacuation order issued, the government encouraged checking evacuation routes and preparing emergency supplies.
Japan is historically susceptible to earthquakes, experiencing around 1,500 annually. While most are minor, catastrophic events, like the 2011 magnitude 9.0 earthquake that caused over 18,000 deaths, highlight the severity of potential dangers.
The Nankai Trough has a troubling history; a large scale earthquake there in 1707 resulted in significant loss of life and triggered an eruption of Mount Fuji. This past haunts current predictions, as experts highlight the importance of historical patterns.
Despite the warnings, experts caution against predictions of exact timing for earthquakes. Robert Geller, professor emeritus of seismology, noted that while the potential for a large quake might be heightened, pinpointing its occurrence remains elusive. The warning system in place, instituted after the 2011 disaster, aims to mitigate future risks, as officials continue to stress preparedness without inciting widespread alarm.
