Japanese authorities have hinted towards the possibility of a "megaquake" striking the northern Pacific coast of Japan in the next week, following a powerful 7.5 magnitude earthquake on Monday. The quake, which struck off Aomori on Japan's northern Honshu coast at a depth of 54 km, caused significant damage. Roads cracked, buildings were damaged, and more than 30 people were injured. The tremor, which was felt as far as Tokyo (roughly 550 km away), also led to the evacuation of nearly 90,000 residents and triggered small tsunamis of about 60-70 cm in height.
The Japan Meteorological Agency (JMA) has raised concerns that the region could experience another tremor, possibly of magnitude 8 or higher. While the probability of such a quake remains low, Japan’s advisory has triggered widespread attention, especially regarding the potential for seismic activity to spread to other parts of the Pacific region.
The Megaquake advisory and its implications
According to Japan's JMA, the "megaquake" advisory is issued when an earthquake of magnitude 7 or higher occurs in known zones where massive earthquakes, known as megathrust quakes, have previously occurred.
This particular advisory, the first ever issued for the Hokkaido–Sanriku sector, indicates a temporary increase in the risk of a larger quake, possibly of magnitude 8 or more, within the next week. However, the likelihood of this happening is still very low, estimated at around 1%.
Japan is situated atop a major subduction zone where the Pacific Plate dives beneath the North American and Okhotsk Plates.
The stress accumulated from this geological activity periodically results in massive earthquakes. In 2011, the country experienced one of the most devastating quakes in history a magnitude 9.0 earthquake that led to a catastrophic tsunami, causing over 20,000 deaths and triggering a nuclear disaster at the Fukushima plant.
The current warning is particularly concerning because Monday’s 7.5-magnitude quake could either be a precursor to a much larger event or part of the ongoing readjustment of stress in the same trench system. Authorities are urging residents and local governments to review evacuation plans, secure emergency supplies, and prepare for the possibility of stronger quakes or tsunami warnings in the coming days.
Will it have an impact on India?
While Japan braces for potential aftershocks, the advisory also serves as a reminder of the shared tectonic vulnerabilities across the Pacific and Indian Oceans. A megaquake off Japan’s coast would primarily affect the northwest Pacific, including parts of Russia’s Far East, the Aleutian Islands in Alaska, and, of course, Japan itself.
However, there are concerns that seismic activity could also trigger tsunamis that may affect other regions, including parts of Southeast Asia and the Indian Ocean.
For India, the direct risk from this specific megaquake event is minimal. Indian scientists point out that India’s coastline is more susceptible to tsunamis generated by megathrusts in the Sunda (Java) Trench near Sumatra or in the Arabian Sea, as evidenced by the devastating 2004 tsunami.
The magnitude 9.1 earthquake off Sumatra in 2004 caused massive loss of life in India, especially in coastal areas of Tamil Nadu, Andhra Pradesh, and the Andaman and Nicobar Islands. That event highlighted the need for effective early-warning systems to mitigate the impact of future tsunamis.
India’s seismic vulnerability
While Japan’s current advisory doesn’t suggest an imminent threat of a megaquake or tsunami for India, it underscores the shared tectonic risks faced by countries around the Indian and Pacific Oceans. India, which has witnessed significant seismic activity in the past, has been working on strengthening its disaster management systems and early warning mechanisms.
The Japanese warning serves as a reminder of the importance of vigilance and preparedness in regions prone to natural disasters.
Experts emphasize the value of international cooperation and knowledge-sharing, especially between countries like India and Japan, both of which lie on the Pacific Ring of Fire. Though the probability of an earthquake of such magnitude impacting India is low, the shared vulnerability makes it essential for both nations to continue advancing their early-warning systems, disaster management plans, and public awareness initiatives to mitigate the potential impact of future seismic events.
