Niue is one of the world’s largest emerged coral atolls. It has been exposed as a result of dropping sea levels and geological uplifting over the last million years. It is 64 kilometres in circumference and 260 square kilometres in area, rising to no more than 69 metres above sea level.
The soils of the island are based on limestone 50 to 500 metres thick, which overlies basalt-type volcanic rock. The ground surface is often jagged with exposed sharp rock outcrops and boulders, with pockets of topsoil varying in depth between them. In some areas there is a thin coating of volcanic ash, the cause of locally high radioactivity.
Although the island is perched on top of an extinct volcano and wide chasms in the limestone show evidence of past seismic activities, there have been no major earthquakes in recent times. However, small earthquakes are not uncommon.
Sources: National Biodiversity Strategy And Action Plan Of Niue, Government of Niue 2001 and Niue by Charles Cooper. Reed Children’s Books, 2000. ISBN 18694884