SOFIA, Bulgaria â€"  The U.S. Geological Survey says a moderate earthquake with a magnitude of 5.6 struck near the Bulgarian capital of Sofia early Tuesday. There are no immediate reports of injuries or significant damage.

The U.S.G.S. said the quake struck shortly after 3 a.m. local time Tuesday near the town of Pernik about 14 miles west of Sofia. The U.S. agency measured its depth at a relatively shallow 5.8 miles.

The agency says an aftershock with a magnitude 4.9 struck the same area about 90 minutes later.