The Cataclysm of The Shattered

An event of unknown origin that destroyed the entire continent of the ancient Tormangi.  Most, but not all, of the Tormangi myths suggest the Great God enacted His wrath by slamming The Lantern onto The World Anvil with such force that the land was overturned and broken into the jumble of islands that exist today.  Modern research has begun to coalesce around the theory that mages from long ago became very adept at gathering Arcanum crystals.  When they had enough they attempted to remake Creation in their image and the resulting failure set up a magical resonance within their continent.  They lost control of it and the whole thing blew apart.  It is also theorized that this event created The Split almost four thousand miles away.