Fears of potential 'megaquake' rise after more than 300 minor earthquakes occur in Japan in 4 days

Around 336 earthquakes have shaken the seas near the Tokara Islands in Kagoshima Prefecture, Japan, from Jun. 21 to 24, sparking fears of a potential "megaquake".

Japan's government agency, the Japan Meteorological Agency (JMA), reported that the quakes are measured at a "shindo" of at least 1 on the Japanese seismic scale.

Shindo, which is measured on a scale from 0 to 7 in Japan, is used to measure the seismic intensity at a specific location.

Six of the earthquakes were at shindo 4, while the strongest earthquake occurred around 5pm on Jun. 22, as reported by local media this week.

The strongest quake, registered as shindo 5.1, occurred on an island just north of Okinawa.

There have been as many as 15 quakes in an hour.

Experts noted that larger quakes may occur, with JMA's Fukuoka regional headquarters warning those in the area to be on alert against earthquakes with strong shaking.

Masashi Kiyomoto, a Meteorological Agency official in charge of earthquakes and tsunamis, said that the region is known for repeated bursts of seismic activity and added that similar clusters occurred in December 2021 and September 2023, as reported by The Japan Times.

While 346 quakes of shindo 1 or higher were recorded in 2023, another 308 were documented in 2021, with one being a magnitude 6.1 quake that reached shindo 5 on Akuseki, one of the Tokara Islands.

Though no tsunami has been reported in connection with any of the quakes, authorities cautioned that a larger event, such as a magnitude 6 or higher earthquake, could heighten such a risk.

Megaquake prediction

Earlier this year, a Japanese government panel issued a prediction that an earthquake with a magnitude of 8.8 would occur near the trench within 30 years.

In the worst-case scenario where the earthquake occurs on a late winter night with few prepared for early evacuation, the government predicted that the natural disaster may lead to up to 298,000 deaths and a loss of up to 270 trillion yen (S$2.43 trillion) in Japan's economy.

"Prophetic" manga

Just earlier this month, Japan holiday bookings reportedly dropped due to a "prophetic" manga that predicted an earthquake in 2025.

A manga novel titled "The Future I Saw" published by Ryo Tatsuki in 1999 had warned that a major disaster would occur in March 2011. This date coincided with the 9.0 magnitude quake that struck Japan's Tohoku region.

In 2021, a reprinted full version of the novel was published, with the sentence “The real disaster will come in July 2025” on the front cover.

Ever since this prediction went viral, airline bookings from Taiwan, South Korea, and Hong Kong have dropped, according to an analysis done by Bloomberg.

While overall tourism to Japan is still going strong, Bloomberg Intelligence's analyst for aviation and defence, Eric Zhu says the quake speculations are "definitely" having a "negative impact" on Japan tourism.

However, Japan Meteorological Agency director general Ryoichi Nomura stated that it is "impossible to predict an earthquake with specific timing, location or its magnitude", and "any such prediction is a hoax, and there is absolutely no need to worry about such disinformation".

Top image via photoAC