Mar. 26 - A large chunk of ice has started to break away from Antarctica's Wilkins Ice Shelf. Wilkins is the largest ice shelf on the Antarctic Peninsula to be threatened so far. Satellite images show the collapse began on February 28 as a massive iceberg fell away from the ice shelf's southwestern front. This lead to a runaway disintegration of the shelf interior. Wilkins Ice Shelf spans about 13,000 square km (5,000 square miles) and is located on the southwest Antarctic Peninsula about 1,600 km (1,000 miles) south of South America. Michelle Carlile-Alkhouri reports.