A megaquake, or megathrust earthquake, is an extremely powerful earthquake, typically magnitude 8.0 or higher, occurring at a subduction zone where one tectonic plate slides under another, causing immense energy release and often generating devastating tsunamis. These quakes involve massive fault ruptures, sometimes over 1,000km long, leading to significant sea floor displacement and widespread destruction, making them the most powerful earthquakes on Earth.
But if it did happen, according to a report by the Japanese government, it would have the potential to produce a tsunami of up to 98 feet high, putting the lives of 200,000 people at immediate risk. So how do we keep people informed without causing a panic?
A 4.7 magnitude earthquake is considered moderate; it's strong enough to be widely felt and cause rattling, but typically results in only minor or no damage, although slight damage can occur to poorly constructed buildings, with significant damage usually starting at magnitude 5.0 or higher.
Japan's separate advisory for an even more damaging megaquake stemming from the Nankai Trough, which affects the southern half of Japan's Pacific coast, was activated for the first time last August after a magnitude 7.1 quake occurred off the eastern coast of Miyazaki.
A manga by artist Ryo Tatsuki predicted a "disaster" in Japan in July 2025. Visits from Asia tourists dropped in June, most notably from Hong Kong. "A fictional narrative amplified by social media could have created a compelling, if scientifically unfounded reason to defer travel," one expert said.
Japan's megaquake risk: What you need to know and should you still travel there? | CNA Explains
Has Japan ever had a 9.0 earthquake?
The magnitude 9.0 earthquake that struck Japan on March 11, 2011, was unprecedented in the modern history of Japan, according to scientists at the U.S. Geological Survey (USGS).
Since 1900, all earthquakes of magnitude 9.0 or greater have been megathrust earthquakes. The thrust faults responsible for megathrust earthquakes often lie at the bottom of oceanic trenches; in such cases, the earthquakes can abruptly displace the sea floor over a large area.
During a Travis Scott concert, seismographs registered ground vibrations equivalent to a 1.3-magnitude seismic event. The reading wasn't an earthquake caused by tectonic movement, but by tens of thousands of fans jumping in unison, sending synchronized shockwaves through the ground.
#1. MAGNITUDE 9.5 (1960). Biobío, Chile - Commonly referred to as the Valdivia earthquake or Great Chilean earthquake, the largest earthquake ever killed 1,655 people and left 2 million homeless.
For powerful quakes of magnitude 7.5 or greater, there is a 37% chance that one or more will occur in the next 30 years in Southern California. Expected Shaking This map builds on the map of likely earthquakes above to show how those earthquakes will shake the region.
Now, a new mystic being dubbed as “Japanese Baba Vanga” – a manga artist by the name of Ryo Tatsuki – is said to have foreseen future tragedies via her graphic novel, The Future I saw, which include an earthquake and resulting tsunami of catastrophic proportions scheduled to hit Japan and surrounding regions on July ...
While many countries around the world lie along earthquake-prone fault lines, there are places where seismic activity is almost nonexistent. According to data, nations such as Belarus, Brazil, Cambodia, Chad, Ivory Coast, Latvia, Mali, and Nigeria are among those that experience very few, if any, earthquakes.
The Ring of Fire is a horseshoe-shaped zone around the Pacific Ocean known for intense seismic and volcanic activity, where tectonic plates collide, causing most of the world's earthquakes and hosting 75% of active volcanoes, including a chain from South America up to North America, across the Bering Strait, down through Japan, and into New Zealand. It's a geologically active area shaped by the movement of tectonic plates, leading to frequent volcanic eruptions and powerful tremors.
On average there are about fifteen earthquakes every year with a magnitude of 7 or greater. As with any quasi-random phenomena, the number of earthquakes each year varies slightly from this average, but in general, there are no dramatic variations.
If the earthquake is right under our feet, we can't warn people because as soon as we notice it, we get rocked. But if it's a big earthquake on the coast or in California, it would take a few minutes for the crack to spread and rupture near us, giving us two, three or four minutes warning.
The Big One is predicted to have a 7.2 large-magnitude and high-intensity [5]. The earthquake is predicted to hit Metro Manila from the West Valley Fault, which is 100 km in length (Fig. 1) and would pass through seven cities in Metro Manila including nearby provinces [6].
It occurred in the afternoon (19:11:14 GMT, 15:11:14 local time), and lasted 10 minutes. The resulting tsunamis affected southern Chile, Hawaii, Japan, the Philippines, eastern New Zealand, southeast Australia, and the Aleutian Islands.
Tsunamis may reach a maximum vertical height onshore above sea level, called a runup height, of 98 ft. (30 meters). A notable exception is the landslide-generated tsunami in Lituya Bay, Alaska in 1958, which produced a 1722 ft. wave (525 m).
From the end of 2024, a rumor began that a great earthquake would occur in Japan in July 2025, based on a purported prophecy in the 1999 manga The Future I Saw by Ryo Tatsuki. Its spread in several Asian countries resulted in a notable decline in holiday travel to Japan. Seismologists discounted the prediction.
