Photo/Illutration Firefighters work to reduce the level of a swollen river in Gifu Prefecture on Aug. 31. (Asahi Shimbun file photo)

Online posts featuring false photos and misinformation about typhoons and heavy rain in summer gained so much attention on X that the Tokyo metropolitan government plans to strengthen countermeasures against such bogus “news.”

Local governments and experts have urged people to look at official information during disasters and avoid relying on what they read from strangers on social media.

However, the rapid spread of false information, including overflowing rivers, during Typhoon No. 10 in August underscored the difficulty of staying ahead of “impression zombies,” who post misleading messages to gain clicks and attention.

The Tokyo metropolitan government already has a tool that monitors and analyzes X postings to gather information in the event of a disaster.

If the posts appear to be hoaxes or misinformation, government officials judge whether such messages could have a significant impact on people’s lives and safety. If risks are perceived, the metropolitan government would alert social media users about the false content.

During Typhoon No. 10, the metropolitan government decided not to alert the public because it determined that the false posts had no significant impact on residents’ safety.

However, officials said the metropolitan government will consider issuing alerts in such cases in the future.

In late August, when heavy rain hit the Kanto region due to Typhoon No. 10, a series of posts on X said, “The Tamagawa river is about to overflow.”

The messages featured pictures of flooding that occurred several years ago or in other countries.

On the morning of Aug. 30, “Tamagawa river flooding” became a leading “trending” topic on X, and these false posts were seen by many more people.

However, according to the land ministry’s Keihin River Office in Yokohama, which has jurisdiction over the Tamagawa river, there was no evidence of flooding in the river.

Tamagawa river flood advisories were issued at 1:20 p.m. on Aug. 30 and again at 1:50 p.m. But both were lifted by 2 p.m. that day, the office said.

Manabu Miyasaka, vice governor of Tokyo, said on his personal X account: “‘Tamagawa river flooding’ is trending on X, and some old photos are being used. Please check the primary information from the official website for data and images.”

Munechika Nishida, an IT journalist, said, “Given the fact that correct information is becoming difficult to find on X, local and national government agencies need to post on several other social networking sites at once to ensure that correct information is disseminated to residents.”

Nishida recommended stronger content moderation, including deletion of troubling posts and displaying the dates and times when posted photos were taken.

He also said information about the poster should be shown, as well as warnings that images may have been created using generative artificial intelligence.

“The central and local governments should also demand that X take action,” he said.

“In times of emergency, we need to be careful about information that is automatically recommended,” Nishida said. “It is important to follow the accounts of your local government, the Japan Meteorological Agency, news organizations, among others, and create a reliable timeline.”

When X was known as Twitter, the platform took root in Japan after the 2011 Great East Japan Earthquake and tsunami. It is now used by tens of millions of people in Japan.

The central and local governments also use X to disseminate information.

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