Kermadec Islands

The Kermadec Islands are a subtropical island arc located in the South Pacific Ocean. They sit northeast of the North Island of New Zealand. They are also a similar distance southwest of Tonga. These islands are part of New Zealand. They are classified as an Area Outside Territorial Authority. Most of the islands are uninhabited. The only exception is the Raoul Island Station. This station is the northernmost inhabited outpost of New Zealand. It serves as a meteorological and radio station. It also provides a hostel for volunteers and Department of Conservation officers.

The islands formed through complex geological processes. They are a volcanic island arc. This arc exists because of a convergent boundary. At this boundary, the Pacific Plate subducts under the Indo-Australian Plate. Subduction means one tectonic plate slides beneath another. This process created the Kermadec Trench. This submarine trench is 8 km deep. The islands sit along the Kermadec Ridge. This undersea ridge runs from Tonga to New Zealand. The four main islands are the peaks of volcanoes. These volcanoes rise from the seabed to reach the surface. Other volcanoes in the chain remain underwater. These are called seamounts. They have between 65 and 1500 m of water above their peaks.

The islands are seismically active due to plate movement. This means they experience many earthquakes. Raoul Island and Curtis Island are both active volcanoes. The other islands are currently inactive. Some are the eroded remnants of extinct volcanoes. In July 2012, the Havre Seamount erupted. It breached the ocean surface from a depth of over 1100 m. This eruption created a large raft of pumice. The islands also face large earthquakes. In 2021, a magnitude 8.1 earthquake occurred. This event caused a tsunami advisory for the North Coast of New Zealand's North Island. It also affected Norfolk Island in Australia.

Human history on the islands began long ago. Polynesian people arrived around the 14th century. They may have visited as early as the 10th century. Their presence is shown by wild taro and candlenut on Raoul Island. The islands were named after Jean-Michel Huon de Kermadec. He was a Breton captain. He visited during the d'Entrecasteaux expedition in the 1790s. In the 19th century, whaling vessels visited the islands. They searched for wood, food, and water. The whaler Fanny visited Raoul Island in 1823. The United Kingdom annexed the islands in 1886. In 1887, they were assigned to New Zealand. European settlers lived there until 1937. The Thomas Bell family lived there from 1878 to 1914.

The climate is subtropical. The mean monthly temperature is 21°C in February. It drops to 17°C in August. Rainfall is about 1100 mm annually. Rainfall is lower from October to January. The islands are a distinct ecoregion. This is known as the Kermadec Islands subtropical moist forests. These forests are part of the Oceanian realm. The canopy is dominated by the Kermadec pōhutukawa. This tree has red flowers. It grows between 10 and 15 metres high. Other canopy trees include the nīkau palm. The forest understory contains shrubs, ferns, and herbs. Many of these plants are endemic. Endemic means they grow nowhere else on Earth. There are 113 native vascular plant species. 23 of these are endemic.

The marine environment is very rich. The islands are an Important Bird Area. They are vital breeding sites for seabirds. These include petrels, sooty terns, and blue noddies. The waters also host many cetaceans. These are marine mammals like whales and dolphins. Humpback whales use the islands as migratory corridors. They travel between here and Antarctica. Other whales include sperm whales and killer whales. Deep-sea hydrothermal vents exist along the Kermadec Ridge. These vents support extremophile communities. These are organisms that live in extreme conditions. One example is the New Zealand blind vent crab.

Conservation is a major concern for the islands. Introduced species have caused damage. Cats, rats, and goats were brought to the islands. Goats overgrazed Macauley Island. This eliminated its forests and created grasslands. Rats and cats preyed on seabirds. This reduced bird colonies from millions to tens of thousands. Scientists work to protect the remaining biodiversity. In 2016, a hawksbill turtle named Koha was released near Raoul Island. She had been nursed back to health at an aquarium. This helped ensure she could orient herself in the ocean. The islands remain a critical site for studying Pacific ecology.