Japan’s seismological experts have elevated their warning system by issuing a rare “megaquake advisory” after a substantial 7.5 magnitude earthquake occurred off the coast of Aomori, adjacent to Hokkaido. Despite the recent tremor causing only minor damage and resulting in 34 injuries, the advisory acknowledges an increased risk of a far more significant seismic event impacting the same area. The agency clarified that the alert is not a prediction but a strategic measure to bolster preparedness, noting that the statistical likelihood of an 8.0+ magnitude earthquake remains statistically low at roughly one percent. This advisory serves as a crucial reminder of the 2011 earthquake and tsunami, which resulted in a devastating loss of nearly 20,000 lives. The JMA highlighted the Hokkaido-Sanriku coast as an area of elevated seismic concern due to its geological setting. A key historical precedent fueling this alert is the observation that the 2011 magnitude 9.0 megaquake was preceded by a 7.3 magnitude quake in the identical seismic zone just two days earlier. Residents in coastal zones across 182 municipalities, from Hokkaido to Chiba Prefecture, are being urged to stay aware, keep emergency supplies readily accessible, and prepare for potential immediate evacuation. The potential consequences of a catastrophic earthquake in this region have been previously estimated, including tsunami waves up to 30 meters, a theoretical death toll of up to 199,000, the destruction of hundreds of thousands of structures, and immense economic repercussions.
