Japan warns of megaquake that could kill 300,000—Is this deep-sea ‘Doomsday fish’ a warning sign?

Japan experiences around 1,500 earthquakes annually, with seismic activity recorded every five minutes

As the death toll from the Myanmar-Thailand earthquake continues to climb, a new report from the Japanese government has issued a stark warning about a potential "mega earthquake" in the Nankai Trough, near Japan’s Pacific coast.

The report cautions that such a disaster could trigger devastating tsunamis, cause massive infrastructure damage, and result in over 300,000 fatalities.

This report came after Myanmar was hit with a 7.7 magnitude of earthquake that has killed over 2900 people. Whereas Japan in 2011 was hit by a 9.0 magnitude Tohoku Earthquake and Tsunami event.

Decoding the megaquake report 

A Japanese government report has warned that a potential magnitude 9 earthquake along the Nankai Trough could cause widespread devastation, triggering massive tsunamis and infrastructural collapse. The worst-case scenario estimates up to 298,000 fatalities, especially if the quake strikes at night during winter.

The report also highlights economic losses reaching 270.3 trillion yen—nearly half of Japan’s GDP—due to inflation-adjusted damage assessments and expanded flood zone projections. Additionally, it warns that 1.23 million people may be forced to evacuate.

Japan issued its first-ever megaquake advisory last year after detecting increased seismic activity near the trough, raising concerns about a heightened risk of a catastrophic quake.

Why is Japan Prone to Mega Earthquakes? Let's understand the Nankai Trough. 

Megaquake is an earthquake with a magnitude of 8 or more. It could create exceptional disaster and also has the potential to generate a tsunami. Whereas Japan in 2011 was hit by a 9.0 magnitude Tohoku Earthquake and Tsunami event that killed at least 20,000 people and massive destruction.

Japan sits along the Pacific Ring of Fire, the world's most seismically active zone. This region includes major tectonic plates such as the Pacific, Philippine, Juan de Fuca, Cocos, and Nazca Plates.

Most of these plates collide and subduct beneath one another, creating intense seismic activity. As a result, Japan frequently experiences powerful earthquakes and tectonic disturbances.

The region of Nankai Trough stretches Japan’s southwest Pacific coast and runs for approximately 900 km (600 miles), where the Philippine Sea Plate is subducting under the Eurasian Plate. The accumulating tectonic strains could result in a megaquake roughly once in 100 to 150 years.

This makes Japan fall in a high risk of major earthquakes, with an 80 per cent chance of a magnitude 8 to 9 quake striking the Nankai Trough.

The Japan Meteorological Agency warns that pressure from the Philippine Sea Plate on the Eurasian Plate in the Nankai Trough could trigger a megaquake and tsunami. As the plates get stuck, they build immense energy, which, when released, may cause devastating earthquakes.

Deep-sea mystery: Can oarfish predict earthquakes and tsunamis?

Interstingly Japanese also relate see the coming of the sea creature to the surface as sign of a major earthquake or tsunami. Japan's folklore has mentions of oarfish as the nickname of "Ryugu no tsukai," or "sea god's palace messenger."

Recent sightings of the elusive oarfish, often called the "Doomsday Fish," have sparked speculation and intrigue. This deep-sea creature, known for its long, ribbon-like body and silver scales, was spotted off the coast of Baja California Sur, Mexico, stirring buzz on social media.

The rare surfacing of oarfish has long fueled fears of impending disasters, especially earthquakes and tsunamis. Deeply tied to Japanese folklore, its recent sightings have many wondering—could this be a sign of something big?