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

An "alert" indicating a massive magnitude-9.9 earthquake sent shockwaves of fear across Japan on Friday afternoon. Just eight minutes after its issuance, the Japan Meteorological Agency retracted the warning, which had been triggered by a lesser magnitude-6.9 quake off the Kamchatka Peninsula in Russia. Although the alert caused temporary disruptions in transportation, officials are now investiga…