The ground shakes for six seconds, in five separate hits, and everything within 10 metres is caught - creatures, doors and placeables. The caster is not.
Each hit rolls a fifth of the total: eight-sided dice, one per caster level up to 15 and one more per three levels after that, so about 4d8 a hit and 20d8 in all at level 40.
A Reflex save halves each hit, and doors and placeables take double.