Austrian authorities say a small earthquake set off a large World War II-era bomb in the garden of a Vienna home. No one was injured in the explosion.

Investigators think the bomb weighed up to half a ton. It lay buried for decades in the garden, and no one knew it was there.

But when a minor quake shook parts of the Austrian capital, the bomb exploded.

Officials say the homeowner heard a dull bang Friday evening and went outside to see what happened. Experts were still on the scene Saturday to examine the crater left by the blast.

Unexploded ordnance from World War II remains strewn across Austria.