Why does Japan experience so many large earthquakes?

By Jessie Yeung, CNN

(CNN) — Almost no other country in the world is rocked by such frequent and damaging earthquakes as Japan – an island nation that sits on the boundary of four tectonic plates, the constantly-shifting slabs of the Earth’s crust.

It also lies on the “Ring of Fire,” a 25,000-mile arc that stretches around the Pacific, where the world’s most active volcanoes are located – and the most earthquakes take place.

The impact of these quakes was on full display this week after a deadly 6.8-magnitude earthquake hit Japan’s southern Kumamoto prefecture, prompting thousands of emergency responders to mobilize in search, rescue and relief efforts.

But Japan is well-prepared for disasters like these, having invested billions of dollars into cutting-edge quake detection technology, response and evacuation systems, and quake-proof infrastructure.

For residents, quakes are a regular part of life – children start practicing earthquake and evacuation drills from kindergarten. But the threat looms large in the public imagination, especially with the government regularly warning that Japan could eventually see a once-in-a-century “megathrust earthquake.”

The latest quake

The quake on Tuesday left at least 14 people dead as of Wednesday, according to CNN affiliate TV Asahi, citing the Kumamoto prefecture and fire department. Others are still unaccounted for and injured, though the total number is unclear.

There are fears that people could still be trapped under damaged or collapsed infrastructure. Many were reportedly trapped and three are still missing after a shopping mall in Kumamoto partially collapsed from an explosion following the quake; authorities have cited a possible gas leak as a cause.

Separately, four workers remain unaccounted for at a paper factory.

Local police and fire departments are now working with military personnel on relief and rescue operations. “People are still waiting for help, and every second counts,” said Prime Minister Sanae Takaichi on Wednesday.

The Kumamoto region had just recovered from a larger quake that hit in 2016, causing widespread damage and killing more than 270 people.

“Why? Why does this keep happening around us here in Kumamoto?” local resident Shoji Yonemitsu told CNN.

“The shaking back then was on a whole different level. But yesterday’s quake was still pretty terrifying,” he said.

Long history of disasters

Japan’s history is littered with devastating quakes.

Throughout its classical and feudal eras, quakes regularly swept through cities and towns, wiping out structures made of wood and paper that were acutely vulnerable to fires breaking out in the aftermath. One particularly damaging quake in 1498 is thought to have killed more than 30,000 people, though estimates differ.

The Great Kanto earthquake of 1923 was another devastating moment, laying waste to swathes of the capital Tokyo and killing some 140,000 people.

Japan began introducing stronger building codes in the 1980s – which demonstrated their effectiveness in the 1995 Kobe earthquake, which killed more than 6,000 people. Nearly all of the collapsed buildings were built prior to the new codes, kickstarting a major drive to improve the country’s quake resilience, emergency response systems, and retrofitting older buildings with new standards.

As one of the world’s wealthiest nations, Japan was in a strong position to embrace technology and spending to fortify itself against the threat of tectonic catastrophes.

But technology can only go so far.

The 2011 Tohoku disaster is the worst in living memory – a magnitude-9.1 earthquake and tsunami that triggered the Fukushima nuclear meltdown and killed nearly 20,000 people. Thousands more were never found. It remains one of the strongest quakes of this century.

Smaller quakes can still routinely bring death; a magnitude-7.1 earthquake killed more than 700 in Noto in 2024, western Japan.

Other countries such as Chile, Indonesia, the Solomon Islands, and the west coast of the United States all lie on the “Ring of Fire” on either side of the Pacific Ocean. It’s where the Pacific Plate – the oceanic plate that lies beneath the water – meets surrounding continental tectonic plates. When these plates move against each other and produce friction, energy builds up and is released through earthquakes.

“About 10% of the world’s earthquakes of magnitude 6 or higher occur in or around Japan, so the risk is much higher than in places like Europe or the eastern United States, where earthquakes are rare,” Shoichi Yoshioka, a professor at Japan’s Kobe University, told CNN in 2024.

“Each time, we witness the tragic loss of lives, buildings being crushed, and tsunamis causing devastation, leaving a lasting impression of fear,” he added. “This fear is likely shared by many citizens. I think this contributes significantly to why Japan is so prepared.”

Is it safe to travel to Japan?

Even among other quake-prone countries, Japan is famed for being a world leader in earthquake preparedness and resiliency.

Buildings are required to have anti-seismic technology, such as walls and floors that can absorb vibrations and shaking, or flexible structures that allow buildings to move during quakes but not collapse. “Most buildings are fairly resistant to earthquakes,” advises one government site for tourists.

But travelers have still been spooked by the threat.

Last summer, a spate of earthquake-related “predictions” caused superstitious travelers across East Asia to cancel or delay their holidays to Japan. These included a Japanese comic book that warned of a “real catastrophe,” a psychic who predicted mass destruction, and a feng shui master who urged people to stay away.

Japan’s government itself has fed these fears – warning for many years that the country could soon see the Nankai Trough megathrust earthquake, the most powerful of its kind.

The Nankai Trough is a 700-kilometer long (435-mile) subduction zone, which refers to when tectonic plates slip beneath each other. Severe earthquakes in this area have been recorded every 100 to 200 years, according to the government’s Earthquake Research Committee.

By calculating the intervals between each major quake, the government has warned there is a 70% to 80% chance that Japan will be rocked by another Nankai Trough earthquake within 30 years, expected to be between magnitude 8 and 9.

But the science is disputed. Some have pushed back against these forecasts, arguing that earthquakes don’t happen in predictable cycles; even those who give credence to the prediction say it’s not necessarily useful to make such long-term, imprecise predictions.

The best thing Japan can do now, several experts told CNN, is to get ready – plugging gaps in parts of the country that are less well-prepared, and raising public awareness on emergency response.

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CNN’s Yumi Asada, Chris Lau, Hanako Montgomery, Nodoka Katsura, Mai Takiguchi and Emiko Jozuka contributed to this report.