On September 4th, a 7.1 magnitude earthquake struck New Zealand. Pictured above is a railroad track that crossed the fault line near Rolleston. Geographer Dave Petley of the American Geophysical Union writes that the buckling may be the result of compressional deformation across a broad zone. The compression on the very strong railway line was accommodated when a weak point was found, leading to a comparatively rapid deformation to form the main buckle on the left. This then concentrated stress on both sides of the buckle, allowing the other (right side) bends to form.