Misinformation about Japan's recent earthquake has been spreading online, leading communications minister Yoshimasa Hayashi to issue a warning.

“I hope everyone will confirm information about natural disasters with what is provided by the central and local governments and media organizations,” he said.

The 7.7-magnitude earthquake struck off the coast of the Tohoku region on April 20, with tremors felt as far away as Tokyo, 330 miles to the south, and triggering tsunami warnings—although these were later downgraded.

However, the quake and tsunami warnings triggered widespread misinformation online. Many YouTube videos showed footage of previous, more severe, earthquakes, including the Noto peninsula earthquake on New Year’s Day 2024 and the 2011 Great East Japan Earthquake.

"Civilians screamed in videos posted to social media after entire homes were flattened during a 7.5 magnitude earthquake in Japan," read one YouTube description.

Many others appeared to be AI-generated.

Other videos showed tsunami waves far higher than those that actually appeared—just two-and-a-half feet—again either AI-generated or recycled from previous quakes.

Many of these originated outside Japan, in South Asia, China and Europe, with the posters using automatic translation into the Japanese language.

Perhaps the most extreme example of misinformation last week was a series of claims that the earthquake had been artificially triggered. A report from Jiji Press, indeed, found more than 6,000 examples on social media, with one post gathering 50,000 views.

Many of these posts linked the quake to the Chikyu deep-sea drilling vessel operated by the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) - even though it was nowhere near at the time. JAMSTEC was forced to issue a statement pointing out that it was completely impossible for drilling activity to cause a quake: "Drilling by a research vessel does not affect the movement of the entire earth," it said.

'Artificial' earthquakes have been a common theme in the past, with one X post in 2024 describing the Japanese people as 'sheep who see this as a coincidence', after the Noto quake.

Playing conspiracy bingo, "No wonder they do as they please with cancer drugs, antihypertensives, vaccines, artificial earthquakes, chemtrails (though I'm somewhat skeptical). They treat us like foolish experimental yellow monkeys," the post continued.

Two years ago, researchers examined such claims, finding, unsurprisingly, that they increased in times of seismic activity. But, they said, "Conspiracy theorists remained relatively active in propagating their theories even during quiet periods without earthquakes."