Japan issues false 9.9 magnitude earthquake warning after quake in Russia but scientists say megaquakes may never happen

Russia’s Kamchatka Peninsula region on Friday was jolted by an earthquake of 7.0 magnitude. The European-Mediterranean Seismological Centre (EMSC) initially estimated it as magnitude of 7.0, but later it was revised to magnitude 6.9. No tsunami warning was issued. However in Japan, a warning was issued for a magnitude 9.9 earthquake. Had such an earthquake occurred, it would have surpassed every earthquake recorded in modern history. The largest earthquake ever recorded was a magnitude 9.5 event that struck Chile on May 22, 1960. The earthquake ruptured a fault extending hundreds of miles along the country’s coast. Although it was not a magnitude 10 earthquake, it remains the strongest earthquake ever instrumentally recorded. And scientists say such megaquakes (technically 10 or above) may never happen.

Can a megaquake ever happen?

According to the United States Geological Survey (USGS), a magnitude 10 earthquake is not considered possible under known geological conditions because no fault long enough to generate one is known to exist.

“The magnitude of an earthquake is related to the length of the fault on which it occurs. That is, the longer the fault, the larger the earthquake. A fault is a break in the rocks that make up the Earth's crust, along which rocks on either side have moved past each other. No fault long enough to generate a magnitude 10 earthquake is known to exist, and if it did, it would extend around most of the planet,” the USGS explains on its website.

Has Japan ever experienced a magnitude 9+ earthquake?

Japan experienced a magnitude 9.1 earthquake in 2011 when a powerful quake struck the Tohoku region. Known as the Great East Japan Earthquake, it triggered a devastating tsunami that killed more than 15,000 people and displaced many others. The disaster also caused the Fukushima Daiichi nuclear accident.

Five earthquakes of magnitude 9 or higher recorded in history

Apart from the 2011 Tohoku earthquake, four other earthquakes of magnitude 9 or higher have been recorded.

Kamchatka, Russia, 1952: A magnitude 9.0 earthquake struck Russia’s Kamchatka Peninsula, becoming the first recorded earthquake of magnitude 9 or higher. It triggered a massive tsunami that reached Hawaii and caused more than $1 million in damage.

Sumatra, Indonesia, 2004: A magnitude 9.1 earthquake off the coast of Sumatra triggered devastating tsunamis across the Indian Ocean. More than 280,000 people died, while millions were affected across South and Southeast Asia and East Africa.

Alaska, United States, 1964: A magnitude 9.2 earthquake struck Prince William Sound on March 27, 1964. Also known as the Great Alaska earthquake or the Good Friday earthquake, it triggered tsunamis and caused widespread destruction, killing 131 people.

Chile, 1960: The largest earthquake ever recorded struck southern Chile on May 22, 1960. The magnitude 9.5 earthquake, also known as the Valdivia earthquake or the Great Chilean earthquake, killed approximately 1,655 people and left around two million homeless.