Japan Removes the “Megaquake” Alert

A week-old warning that a “megaquake” with the potential to cause enormous damage and fatalities was lifted on Thursday in Japan. The government informed the public that their lives could now “go back to normal.”

A warning that such a disaster would strike the 125 million-person island caused thousands of Japanese citizens to postpone holidays and stock up on necessities, clearing shelves in some supermarkets.

Disaster management minister Yoshifumi Matsumura stated, “The special call for attention ended at 5:00 pm (0800 GMT) since there were no abnormalities detected in seismic activity and crustal deformation.”

Matsumura informed reporters, “But it doesn’t mean the risk (of a major earthquake) has been eliminated.”

“We have been requesting extra safety measures, like sleeping while ready to flee right away. However, we will no longer be requesting these actions, and Japanese citizens are free to resume their regular lives.

The probability of a megaquake was deemed “higher than normal” by Japan’s meteorological service on Thursday, the day after a magnitude 7.1 tremor earlier in the day left 15 people injured.

That was a subduction megathrust earthquake, a type of tremor that has historically happened in pairs and has the potential to cause enormous tsunamis.

The warning pertained to the Pacific Ocean’s Nankai Trough, which lies between two tectonic plates.

The 800-kilometer (500-mile) underwater ravine runs parallel to the Pacific coast of Japan, passing through the Tokyo region, which is home to some 40 million people and is the world’s largest metropolitan area.

When the Nankai Trough broke in three parts at once in 1707, the resulting earthquake is still the second-strongest on record for the country.

Following the earthquake, which also caused Mount Fuji’s final eruption, there were two strong Nankai megathrusts in 1854 and one each in 1944 and 1946.

Trains moving more slowly
According to earlier estimates from Japan’s government, there is an approximately 70% chance that the next magnitude 8–9 megaquake along the Nankai Trough would occur within the next 30 years.

Experts predict that in the worst-case scenario, 300,000 lives might be lost; however, other engineers believe that the damage could be as high as $13 trillion, with infrastructure completely destroyed.

The agriculture and fisheries ministry asked citizens on Saturday “to refrain from excessively hoarding goods,” although experts indicated the risk remained low.

The announcement was made when the demand for emergency supplies like portable toilets and stored food skyrocketed online and stores placed restrictions on sales, including bottled water.

Prime Minister Fumio Kishida even canceled a four-day trip to Central Asia that was scheduled to take place last weekend because to the megaquake warning.

Authorities ordered nuclear reactors to double-check their emergency plans, while some bullet trains slowed down as a precaution.

“Strikingly convincing”
Japan is situated atop four major tectonic plates, and experiences about 1,500 earthquakes annually, the majority of which are mild.

The impact of even the largest earthquakes is usually minimized because of modern construction methods and well-honed emergency protocols.

First under new regulations, the Japan Meteorological Association (JMA) issued its warning following the 2011 earthquake, tsunami, and nuclear accident that claimed around 18,500 lives.

At the Fukushima nuclear facility, the 2011 tsunami caused three reactors to melt down, leading to the greatest nuclear accident in history and the deadliest disaster in Japan since Chernobyl.

Geologists Kyle Bradley and Judith A. Hubbard stated in their Earthquake Insights email this week that “the history of great earthquakes at Nankai is convincingly scary.”

However, Bradley and Hubbard stated that there was only a “small probability” that the magnitude 7.1 earthquake that occurred last week was a foreshock.

“One of the difficulties is that there is never a high chance of a second earthquake,” they stated.