A fake quake warning in Tokyo, Japan, on Friday alerted millions of residents that a “strong” earthquake was about to hit, but the alarm was triggered in error by two minor quakes.
The J-Alert system warned of a large quake shortly after the two quakes with preliminary magnitudes of 4.4 and 3.9 occurred at 11:02 a.m. in the eastern and central Japan prefectures of Ibaraki and Ishikawa, respectively.
The system, which alerts the public, local officials and media of natural disasters and other threats, only issues a warning if a quake measuring lower 5 or higher on the Japanese seismic intensity of 7 is predicted, but the two quakes on the opposite sides of the main island of Honshu measured 3 or less, according to the Japan Meteorological Agency.
The two quakes were 3 seconds apart and the J-Alert processed their seismic waves as those originating from the same temblor, the agency said.
The J-Alert system issues advisories for areas expected to register seismic intensity levels of 4 or higher. There have been cases when quakes registering no more than 1 on the intensity scale have triggered emergency warnings.