Tokyo residents had good reason to be scared Monday morning. Thousands were told a 9.1-magnitude earthquake was imminent. That's strong enough to level a city.
But apparently it was a false alarm -- Japan's Meteorological Agency sent out the alert and then immediately took it back. But it wasn't fast enough to stop weather apps from sending scary notifications.
An agency official said lightning may have hit a seismograph, causing the false alarm.
It wouldn't be Japan's first 9.0 or higher quake. A 9.0 quake triggered a tsunami in 2011 that killed 18,000 people.
That included this disaster-warning app, Yurekuru, with at least 5 million downloads to date.
Once the error was realized, some tried to respond with humor.
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