What was the Great Sundering in World of Warcraft

The Great Sundering was when the Well of Eternity exploded, and tore the continent now known as "Old Kalimdor" into three pieces; Eastern Kingdoms, Northrend and Kalimdor. The Maelstrom in the middle of these continents is where the Well of Eternity used to be, and all the continents where joined together there.