The weekend weather was expected to be much warmer and parade organizers wanted to give the region a taste of what they have to offer. They put the word out underground reaching down to the fault line. Caves caverns and tunnels beneath the city of dirty muddy writhing masses. The displacement of gravity near the fault deep below the Earth surface led to the seismic shift and resulted tectonic plate movement.
They started climbing up and as the dirt caved in at the surface the cracks gave way to the crater that formed. Oh yeah it was way worse than the big one a year or so ago everyone knew it would be. It was going to happen. Everybody had moved over here after nightfall. There will be plenty to eat for generations.