Kermadec Islands

map of the Kermadec Islands

Raoul Island from space

The Kermadec Islands are an island arc in the South Pacific Ocean. The islands have been part of New Zealand since 1887.

The islands lie within 29° to 31.5° south latitude and 178° to 179° west longitude, 800 – 1000 km northeast of New Zealand's North Island, and a similar distance southwest of Tonga. The centre of the Kermadec Islands group is located at approximately 29°16′37″S 177°55′24″W.

Geography

The group includes four main islands (three of them might be considered island groups, because the respective main islands have smaller islands close by) and some isolated rocks, which are, from North to South:

• Raoul or Sunday Island is by far the largest of the Kermadec Islands. Raoul Island is located at 29°16′0″S 177°55′10″W, 900 km SSW of 'Ata, the southernmost island of Tonga, and 1100 km NNE of New Zealand. Raoul island has an area of 29.38 km² with numerous smaller satellite islands, Moumoukai peak, 516 m high)
• Macauley Island, the second largest (located at 30°14′S 178°26′W, 110 km SSE of Raoul Island, Mount Haszard with an elevation of 238 m, area 3.06 km² with neighboring island: Haszard Island)
  • Macdonald Rock, about 4 km north of Macauley Island at 30°11′S 178°26′W
• Curtis Island, the third largest (located at 30°32′32″S 178°33′39″W, 35 km SSE of Macauley Island, 137 m high, area 0.59 km² with neighbouring Cheeseman Island)
• L'Esperance Rock, formerly French Rock (80 km SSE of Curtis Island at 31°26′S 178°54′W, 250 m in diameter, 0.05 km² in area, 70 m high)
  • L'Havre Rock, about 8 km NNW of L'Esperance Rock near 31°21′S 178°59′W (submerged, barely above water during low tide)

Seamounts North and South of the Kermadec Islands are an extension of the ridge running from Tonga to New Zealand (see Geology).

• Star of Bengal Bank, 103 km SSW of L'Esperance Rock, with a least depth of 48 meters

The total area of the islands is 33.08 km². The islands are uninhabited, except for the permanently manned Raoul Island Station, a government meteorological and radio station and hostel for Department of Conservation officers and volunteers that has been maintained since 1937 on the northern terraces of Raoul Island, about 50 m in elevation above the cliffs of Fleetwood Bluff. Raoul Island Station represents the northernmost outpost of New Zealand.

The climate of the islands is subtropical, with a mean monthly temperature of 22.4 °C in February and a mean monthly temperature of 16.0 °C in August. Rainfall is approximately 1,500 mm annually, with lower rainfall from October through January.

Geology

Bathymetry of the Kermadec volcanic island arc and surrounding areas

The islands are a volcanic island arc, formed at the convergent boundary where the Pacific Plate subducts under the Indo-Australian Plate. The subducting Pacific Plate created the Kermadec Trench, an 8 km deep submarine trench, to the east of the islands. The islands lie along the undersea Kermadec Ridge, which runs southwest from the islands towards the North Island of New Zealand and northeast towards Tonga (Kermadec-Tonga Arc). The four main islands are the peaks of volcanoes that rise high enough from the seabed to project above sea level. There are several other volcanoes in the chain that do not reach sea level, but form seamounts with between 65 and 1500 m of water above their peaks. Monowai Seamount, with a depth of 120 m over its peak, is midway between Raoul Island and Tonga. 100 km south of L'Esperance Rock is the little-explored Star of Bengal Bank, probably with submarine volcanoes. Further south are the South Kermadec Ridge Seamounts, the southernmost of which, Rumble IV Seamount, is just 150 km North of North Island of New Zealand. The ridge eventually connects to White Island in New Zealand's Bay of Plenty, at the northern end of the Taupo Volcanic Zone. The islands experience many earthquakes from plate movement and volcanism.

Raoul and Curtis are both active volcanoes. The volcanoes on the other islands are currently inactive, and the smaller islands are the eroded remnants of extinct volcanoes.

Kermadec Islands subtropical moist forests

The Kermadec scalyfin - part of a rich marine biota at the Kermadecs

The islands are recognized by ecologists as a distinct ecoregion, the Kermadec Islands subtropical moist forests. They are a tropical and subtropical moist broadleaf forests ecoregion, part of the Oceania ecozone. The forests are dominated by the red-flowering Metrosideros kermadecensis, relatedhbbb gvfvffvffdfff to the Pōhutukawa (M. excelsa) of New Zealand. The islands have no native land mammals, but were home to vast numbers of seabirds which nested among the forests.

Flora

Kermadec islands are home to 113 native species of vascular plants, of which 23 are endemic, along with mosses (52 native species), lichens and fungi (89 native species). Most of the plant species are derived from New Zealand, with others from the tropical Pacific.

Dense subtropical forests cover most of Raoul, and formerly covered Macauley. Metrosideros kermadecensis is the dominant forest tree, forming a 10 – 15 meter high canopy. An endemic Nikau Palm (Rhopalostylis cheesemanii) is another important canopy tree. The forests had a rich understory of smaller trees, shrubs, ferns, and herbs, including Myrsine kermadecensis; Lobelia anceps, Poa polyphylla, Coprosma acutifolia, and Coriaria arborea. Two endemic tree ferns, Cyathea milnei and the rare and endangered Cyathea kermadecensis, are also found in the forests.

Areas near the seashore and exposed to salt spray are covered by a distinct community of shrubs and ferns, notably Myosporum obscurum, Coprosma petiolata, Asplenium obtusatum, Cyperus ustulatus, Disphyma australe, and Scirpus nodosus.

152 non-native species of plants introduced by humans have become established on the islands.

History

Polynesian people settled the Kermadec Islands in around the fourteenth century (and perhaps previously in the tenth century), but when Europeans reached the area in 1788 they found no inhabitants. The islands were named for the French captain Jean-Michel Huon de Kermadec, who visited the islands as part of the d'Entrecasteaux expedition in the 1790s. European settlers, initially the Bell family, lived on the islands from the early nineteenth century until 1937, as did whalers. One of the Bell daughters, Elsie K. Morton, recounted the family's experience there in her memoir, Crusoes of Sunday Island. Since then, a government meteorological and radio station and hostel for Department of Conservation officers and volunteers have been maintained on Raoul Island.

Conservation

Introduced cats, rats, and goats devastated the forests and seabirds. Overgrazing by goats eliminated the forests of Macauley Island, leaving open grasslands, and altered the understory of Raoul Island. Predation by rats and cats reduced the seabird colonies on the main islands from millions of birds to tens of thousands. The New Zealand government has been working for the last few decades to restore the islands. New Zealand declared the islands a nature reserve in 1937, and the sea around them a marine reserve in 1990. Goats were removed from Macauley in 1970 and from Raoul in 1984, and the forests have begun to recover. The islands are still known for their bird life, and seabird colonies presently inhabit offshore islets, which are safe from introduced rats and cats. Efforts are currently underway to remove the rats and cats from the islands, as well as some of the invasive exotic plants.

Visits to the islands are restricted by the Department of Conservation. The Department allows visits to Raoul by volunteers assisting in environmental restoration or monitoring projects, and other visitors engaged in nature study. Visits to the other islands are generally restricted to those engaged in scientific study of the islands.

Earthquakes

On May 16, 2006 at 22:39 hours, NZDT, a 7.6 earthquake hit the region and was felt as far away as Christchurch.

On September 29, 2008 a 7.0 magnitude quake struck off New Zealand's Kermadec Islands. It was followed by three more of comparable magnitude before the end of the year.

On February 19, 2009 a 7.0 magnitude quake struck off the Kermadec Islands in NOAA's region 2154Z.

On May 15, 2009 a 6.5 magnitude quake struck off the Kermadec Islands at 31.522°S, 178.887°W, just to the south and west of L'Esperance Island.

See also

• 2007 Tonga earthquake

External links

• Kermadec Islands subtropical moist forests (World Wildlife Fund)
• Kermadec Marine Reserve (New Zealand Department of Conservation)
• Kermadec Islands Marine Reserve (Seafriends): geography, history, ecology, natural history, diving (80pp)