Japan issued warning for "mega earthquake" above 8 on the Richter scale

Japan has issued a warning about an elevated risk of a "mega-earthquake" and residents in the affected area are being urged to have an evacuation plan in place after a magnitude 7 earthquake last Thursday. 

In Japan, old fears of "the big one" is now being rekindled after a recent large earthquake. 

"We’ve been told for so long that 'The Big One' will come one day, so I ask myself: Is this it?"  Masayo Oshio, resident of Yokohama, said to the BBC.

A mega-earthquake is defined as an earthquake with a magnitude of over 8 on the Richter scale.

"There’s no doubt that it will happen, but the question is when," says seismologist Björn Lund to SVT.se. 

On Thursday August 8, a powerful earthquake with a magnitude of 7 on the Richter scale struck the Nankai Trough, an underwater zone along Japan’s Pacific coast.

For the first time ever, Japan has now issued a warning of an increased risk for a mega-earthquake in the area.

The warning  is partly due to the fact large earthquakes, like the one on Thursday, reportedly can be followed by even bigger mega-earthquakes, as was the case in 2011 during the major earthquake affecting Fukoshima. 

However, the warning indicates only that the risk has increased, and does not necessarily mean that a major earthquake is expected in the coming days. Authorities have, for instance, advised residents not to stockpile goods.

As late as in January 1st, 2024, a large earthquake caused wide spread destruction in Japan, according to Wikipedia.com.  

At 16:10 JST (07:10 UTC), a powerful MJMA 7.6 (Mw 7.5) earthquake struck 6 km (3.7 mi) north-northeast of Suzu on the Noto Peninsula, Japan. 

The severe shaking and resulting tsunami caused widespread devastation across the Noto Peninsula, particularly in the towns of Suzu, Wajima, Noto, and Anamizu. Neighboring prefectures, including Toyama and Niigata, also suffered significant damage.

The earthquake resulted in 339 confirmed deaths, with three people still missing, all in Ishikawa. Over 1,300 individuals were injured, and 156,526 structures were damaged across nine prefectures. This earthquake is the deadliest in Japan since the 2011  earthquake and tsunami.

Japan is one of the most earthquake-prone countries in the world. The nation sits on the Pacific Ocean’s "Ring of Fire," a horseshoe-shaped zone of volcanoes where approximately 90 percent of the world's earthquakes occur.

In 2011, more than 15,000 people lost their lives in a magnitude 9 earthquake in northeastern Japan, which triggered a tsunami and led to three nuclear reactor meltdowns at the Fukushima nuclear power plant.

The Nankai Trough has historically experienced several powerful earthquakes, the most recent occurring in 1946. That quake, with a magnitude of 8, triggered a 6.9-meter tsunami and killed over 1,300 people, according to Reuters.

The Japanese government previously assessed that there is a high probability of a mega-earthquake, potentially reaching a magnitude of 9.1, occurring in the area within the next 30 years.

Photo Credits:

 Cover Photo above:  A drone searches through the remains of collapsed buildings after the Noto earthquake in January 2024. Photo by the Japan Ministry of Defence. Wikipedia Commons License

Second photo in text: Aid being distributed by military after the 2024 Noto earthquake Photo by the Japan Ministry of Defence. Wikipedia Commons License