Whakaari / White Island ([faˈkaːɾi], Māori: Te Puia Whakaari, lit. "the dramatic volcano"), also known as White Island or Whakaari, is an active andesite stratovolcano situated 48 km (30 mi) from the east coast of the North Island of New Zealand, in the Bay of Plenty. The island covers an area of approximately 325 ha (800 acres), which is just the peak of a much larger submarine volcano.
The island is New Zealand's most active cone volcano, and has been built up by continuous volcanic activity over the past 150,000 years. The nearest mainland towns are Whakatāne and Tauranga. The island has been in a nearly continuous stage of releasing volcanic gas at least since it was sighted by James Cook in 1769. Whakaari erupted continually from December 1975 until September 2000, and also erupted in 2012, 2016, and 2019.
Sulphur was mined on the island until the 1930s. Ten miners were killed in 1914 when part of the crater wall collapsed.
A large eruption occurred at 14:11 on 9 December 2019, which resulted in 22 fatalities, including two people who were missing and ruled to be dead by a coroner. Twenty-five survivors were injured, many critically and with severe burns. Forty-seven people were reportedly on the island when it erupted. A second eruption closely followed the first.
Whakaari / White Island is an irregular oval in shape, with a length (northwest–southeast) of 3 kilometres (1.9 mi) and a width of 2 kilometres (1.2 mi), and covers an area of approximately 325 hectares (800 acres). It lies in the Bay of Plenty 48 kilometres (30 mi) from the North Island mainland, due north of the town of Ōpōtiki and north-northeast of Whakatāne. The island's active crater lies slightly southeast of the island's centre, and contains an acidic lake. The crater has a sharp rim to the northwest, with its highest point (also the island's highest point) being the 321-metre (1,053 ft) Mount Gisborne in the west. The 283-metre (928 ft) Mount Percival forms the northern part of the rim. An older vent, the 310-metre (1,020 ft) Mount Ngatoro, lies to the northwest. The exposed island is only the peak of a much larger submarine volcano, which rises up to 1,600 m (5,249 ft) above the nearby seafloor.
The island is generally rugged, with cliffs surrounding most of the coast. The only exceptions are to the southeast of the crater, where ash and boulder slopes descend to Te Awapuia Bay (also known as Crater Bay), the site of derelict buildings and the island's wharf. This bay lies between a prominent headland, Troup Head, at the island's southeastern extreme, and the island's southernmost point, Otaketake, which is the site of one of the island's gannet colonies. Another colony exists at Te Hokowhitu, the cliff which forms much of the western coast of the island.
Several rock reefs and islets are located along the island's northeast coast, and there is also a rock reef at Troup Head. A small islet, Club Rocks, lies 800-metre (2,600 ft) south of Otaketake Point. It consists of a set of four sea stacks rising to more than 20-metre (66 ft) above sea level. In addition, four sea stacks collectively known as Te Paepae o Aotea or Volkner Rocks lie 5 kilometres (3.1 mi) northwest of Whakaari / White Island. Three of these sea stacks rise precipitously from the sea floor (less than 100 metres (330 ft) below sea level) to a maximum height of 113 metres (371 ft) m above sea level. The fourth sea stack is just an eroded stump.
Whakaari / White Island is an andesite–dacite stratovolcano that consists of two overlapping volcanic cones, which are the Ngatoro and Central cones. The Ngatoro Cone is extinct and partially eroded. The amphitheatre-shaped Central Cone is an active cone. The crater of Central Cone is open to the southeast as the result of major, past flank landslides involving hydrothermally altered rock and past phreatic and phreatomagmatic eruptions. the Ngatoro Cone and Central cones are both constructed of alternating layers of lava flows, tuffs, agglomerates, tephra, igneous dikes, and breccias. Some of these strata have been altered to varying degrees by highly corrosive and acid hydrothermal fluids and gases.
The modern crater floor of Whakaari / White Island lies less than 30-metre (98 ft) above sea level and is largely covered by material from the 1914 debris avalanche. The main crater contains three coalescing sub-craters. The sub-craters are aligned NW-SE within the amphitheatre-shaped Central Cone. The open sea breaches the south-eastern crater wall in three places to form Shark, Te Awapuia, and Wilson bays, which Troup Head and Pinnacle Head separate from each other. Long-lived, semi-continuous, weak, hydrothermal explosions, similar to those occurring in the Western sub-crater today, are regarded to have formed these three bays as hydrothermal explosion craters.
Whakaari / White Island and the sea stacks that form Club Rocks and Volckner Rocks are the emergent summits of a larger, 16 by 18 kilometres (9.9 by 11.2 mi), submarine volcano. It is known as White Island Volcano and has a total volume of 78 km3 (19 cu mi). The bathymetry surrounding the emergent summit of Whakaari / White Island consists of a broad, sloping shelf extending from sea level to approximately 80-metre (260 ft) depth. Steep margins define the extent of the submarine volcano at a depths of 300–400-metre (980–1,310 ft)
The amphitheatre-shaped crater of the modern Central Cone is argued to have been created by the collapse of the former cone of the White Island Volcano to the southwest. Based on extrapolating 20 m GIS contour data to enclose the present crater and upwards with a maximum slope angle of 30°, the former pre-collapse summit was inferred to have been 500–600-metre (1,600–2,000 ft) high. Side-scan and bathymetric data indicate possible debris flows associated with its collapse that can be traced back to the current crater on White Island. One of these debris flows exited the crater on the southern side of Troup Head and towards the southeast. It produced well-defined boulder-covered lobes on the seafloor. Another debris flow exited the modern crater on the northern side of Troup Head and through several submarine valleys towards the east into deep water. It produced boulder-covered valley-fill deposits. The latter debris flow was large enough to have produced a significant tsunami. As a result of the collapse of the former cone of the White Island Volcano, it is suspected to have generated a 7-metre (23 ft) high tsunami that flooded the coast of Bay of Plenty as much as 7 kilometres (4.3 mi) inland between 3,000 and 2,200 B.P.
Whakaari / White Island lies in the northern end of the Taupō Volcanic Zone. The Taupō Volcanic Zone forms the southernmost segment of the 2,800 km (1,700 mi)-long Tonga–Kermadec–Taupō volcanic arc system and the Lau Basin–Havre Trough–Ngatoro Basin back-arc basin system.
For the past few thousand years, Whakaari / White Island has been the location for an open, highly reactive hydrothermal system. This hydrothermal system expresses itself as hot springs and mud pools, fumaroles, and acid streams and lakes. The present centre for volcanic activity and outgassing is a large crater lake of boiling acidic waters located in the western subcrater. The intermixing mélange of marine waters, meteoric waters, and hot magmatic fluids generate acid brines, with pH as low as 2, that outgas and form numerous and often transitory hot springs and mud pools, fumaroles, and acid streams and lakes. The crater lake of boiling acidic water, which occupies the western subcrater, appears to vary in volume due to changing meteorological conditions and fluctuating levels of hydrothermal activity.
Although Strombolian activity occurred from the late seventies to the mid-eighties, explosive eruptions at Whakaari / White Island are typically phreatic or phreatomagmatic in style. The lava flows, ash, and pyroclastic flows produced by historic and prehistoric eruptions are andesitic and dacitic in composition. These eruptions also produce discrete craters within crater-fill deposits of the Central Cone. Since 1826, there has been a minimum of 28 phreatic or phreatomagmatic eruptions. In addition, prehistoric eruptions have also extruded lava. The lava flows from these prehistoric eruptions are exposed crater walls of the Central Cone. Whakaari / White Island's frequent activity and easy access attract scientists and volcanologists as well as many tourists. For example, this volcano provides a readily studied example of the type of volcanic magmatic–hydrothermal system involved in the generation of porphyry copper deposits.