A remote volcanic island has erupted in the South Pacific, promting an emergency evacuation. The explosion on the New Zealand territory of Raoul island in the Kermadec chain has left one man missing.

A New Zealand Department of Conservation (DOC) official said: "A helicopter has been sent to pick up the DOC staff that are based on the island, five of whom have been accounted for. One staff member is missing after going on a routine mission."

Rescuers trying to locate the unaccounted for worker have been beaten back by the eruption. A spokesperson said: "Two staff members on the island attempted to search the area where the missing person was thought to be but had to retreat due to further volcanic activity and the track being impassable with fallen trees and ash."

The plan is to refuel the helicopter and try again on Saturday.

Clusters of small earthquakes had been reported on Raoul earlier this week but had fallen off close to the explosion. The tremors were centred 12 to 15 km away from the island itself. There were apparently no warning signs of increased volcanic activity on Raoul itself. The last time Raoul erupted was back in 1964 (pictured above).

The eruption of Raoul's Green Lake, a water-filled caldera, began at 8.21am Friday local time. The missing researcher had gone to check the water temperature. The blast was accompanied by a mild earthquake, estimated at three to four on the Richter scale.

The Kermadec Islands lie about 1,000km northeast of Auckland on the Kermadec trench, part of the Pacific Ring of Fire. The Australasian tectonic plate meets the Pacific plate at the base of the trench. The vulcanism is produced as the Australasian plate collides with its neighbour forcing it under - a process called subduction. ®

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