The Temblor

The Temblor is a natural phenomenon caused by The Volei (Magic in Valmautéra). It manifests as great convulsions of the earth, during which entire cities can be sucked down into The Shattergloom or whole cavern systems pushed to the surface of the world.
Temblors range in ferocity and size. They may occur slowly over a period of days or weeks, or they may occur suddenly and entirely without warning. Temblors may be mild in effect, tilling small areas of surface soil, or they may manifest as convulsions that entomb entire cities. However, they do share some degree of predictability; wherever The Volei is strongest, The Temblor is at its height. As such, the people of Valmautéra tend to avoid areas of arcane power. More importantly, as sentient beings excite the ebb and flow of magic, large settlements tend not to last too long before being struck by The Temblor (with few, notable exceptions).