Japan Quake: 7.5 Magnitude & Mega-Tsunami Advisory Issued

Japan has issued a megaquake advisory following a magnitude 7.5 earthquake that struck off the eastern coast of Aomori prefecture. Officials say the advisory, announced Tuesday, is not a prediction, but aims to prepare the public for a potentially devastating quake similar to the 2011 disaster.

Megaquake Advisory Issued for Northern Japan

Damage from the recent earthquake was limited, with 34 mostly minor injuries reported and some damage to roads and buildings. However, officials indicated an increased risk of a magnitude-8 or larger quake within the next week, particularly for residents in coastal areas.

The Japan Meteorological Agency (JMA) stated that Monday’s quake temporarily increased potential risks in the regions of Hokkaido and the Sanriku coast. These areas are located where the Pacific plate beneath Japan forms the Japan and Chishima trenches, which have historically been the source of large earthquakes.

Experts note that the 2011 earthquake and tsunami, which claimed nearly 20,000 lives, was caused by movement associated with the Japan Trench. That quake occurred two days after a magnitude 7.3 temblor in the same trench.

The 2011 tsunami reached heights of over 15 metres (50 feet) in some areas, causing significant damage, including to the Fukushima Daiichi nuclear power plant.

Potential Impact of a Future Megaquake

A future megaquake in the Hokkaido-Sanriku area could potentially cause a tsunami up to 30 metres (98 feet) high, resulting in as many as 199,000 fatalities, the destruction of up to 220,000 homes and buildings, and an estimated 31 trillion yen ($198 billion) in economic damages, according to government estimates.

The advisory covers 182 municipalities from Hokkaido to Chiba prefecture. Officials emphasize that the advisory does not predict a megaquake at a specific time or location, but rather encourages preparedness.

Residents are being urged to remain cautious and prepared while continuing their daily routines. They are advised to assemble emergency bags containing essential supplies, including shoes and helmets, and to discuss evacuation plans with family members. People are also advised to sleep in day clothes, and secure furniture to walls and floors.

Local authorities are taking proactive steps, such as Iwaki city in Fukushima urging residents to register for emergency email alerts, and officials in Oarai, Ibaraki prefecture, inspecting wireless communication devices.

A similar megaquake advisory issued in the summer of 2024 led to ambiguity and panic buying of emergency supplies, event cancellations, and business closures. The latest advisory aims to avoid similar disruptions by providing clearer guidance.

Many people postponed planned trips and rushed to stock up on essential goods, leaving shelves empty in some areas.