Almost a year after the Japanese Tohoku earthquake and megatsunami, the Pacific Ocean is still dealing with the consequences of the catastrophe.

A mass of debris was washed out to sea as flood waters receded from the land, and some of that wreckage continues to float around the ocean.

Modelling work by the Hawaii-based International Pacific Research Center suggests the debris field has travelled some 2,000 nautical miles (almost 4,000km) to the east of Japan.