Across the Kanto region and in parts of Fukushima Prefecture, alarms suddenly rang out at 11:02 a.m. Friday from cellphones and public speakers.
“Emergency earthquake warning,” the text of the cellphone alert from the Meteorological Agency read. “An earthquake has occurred off the coast of Ibaraki. Prepare for strong shaking.”
But the jolt never came to the region.
The agency had estimated that a magnitude 6.4 earthquake would hit off the coast of Ibaraki Prefecture.
In fact, that quake was magnitude 4.4 and 3 on the Japanese intensity scale. But at the same time, a second quake hit Toyama Prefecture, this one a magnitude 3.9 that also measured 3 on the Japanese scale.
The erroneous warning — and unnerving alarms — came as a result of the two quakes being processed by the prediction system as one event, a statement released by the Meteorological Agency said. The agency said it will further investigate the incident and make efforts to improve the system.
Earthquake Early Warning (EEW) alerts are issued by the agency when its system predicts earthquakes hitting lower 5 or higher on the Japanese intensity scale. Alerts are sent to personal phones, public speakers, radios and televisions in all the regions predicted to experience level 4 shaking or stronger.
Friday’s warning was also sent to 84 loudspeakers in public locations across Shibuya Ward.
“We have received several complaints and inquiries asking why the warning of big earthquake was announced despite the fact that the quake was too small to feel,” said Toshiaki Hidaga, director of the ward’s disaster prevention division.
The ward later sent out a message to its residents explaining how the EEW system works and the reasons for sending out such warnings.
On Twitter, users offered mixed reactions to the scare. Some complained about the alert, with user @tetraetra saying the alarm was risky for people with heart trouble, adding, “Who asked for this sound?”
Others, including user @chokoota3, said they appreciated the system and said it was wrong to complain about the warning as it served as a reminder to always be prepared.
In August 2016, a similar false alarm resulted in alerts warning of a quake measuring 7 on the Japanese scale, the most powerful level.