Japan issued a 9.9 magnitude earthquake alert, but ground didn't shake: What happened

Japan triggered widespread alarm on Friday after its earthquake early warning system "announced" a magnitude-9.9 earthquake alert, prompting emergency phone alerts, public loudspeaker warnings and television broadcasts urging people to take shelter, before the warning was withdrawn eight minutes later.However, no major shaking followed the alert, which the Japan Meteorological Agency (JMA) later attributed to errors in its earthquake magnitude estimation and location calculations. The agency is investigating the cause of the malfunction, reportd Japan Times.The alert was issued at 12.40 pm (local time), two minutes after a magnitude-6.9 earthquake struck off Russia's Kamchatka Peninsula.