Story: Historic volcanic activity
Page 1 – Eruptions in early history
The Taupō eruption
The serene waters of Lake Taupō in the central North Island mask a violent past – beneath the lake lies an enormous volcano. About 200 AD it unleashed the world’s most powerful eruption in 5,000 years.
During the main eruption, the volcano sent up a plume of dust and gases 50 kilometres into the stratosphere. Vast clouds of gases and 30 cubic kilometres of glowing-hot pumice and ash were blasted into the sky. The towering column collapsed suddenly, and hot ground-hugging pyroclastic flows raced away from the vents at 600–900 kilometres per hour. These incandescent clouds incinerated everything in an area of 20,000 square kilometres. These would have caused spectacular sunsets and several years of cooler temperatures worldwide.
No people lived in New Zealand at the time of the Taupō eruption – Polynesian seafarers did not settle the country for another 1,000 years.
Volcanoes provide clues as to when the first Polynesians, the ancestors of Māori, came to New Zealand. They are thought to have arrived about 1250–1300 AD. When Tarawera erupted around 1314 AD it deposited a widespread layer of ash, known as Kaharoa ash. Pollen lying just below the ash at a few sites suggests that small areas of forest may have been cleared before the eruption, and remains of occupation found by archaeologists immediately above the ash indicate that small numbers of Polynesians may have been living there.
Māori people living in New Zealand before Europeans arrived would have witnessed the eruptions of Tarawera, Rangitoto, Taranaki (Mt Egmont), Tongariro, Ngāuruhoe, Ruapehu and Whakaari (White Island).
Rangitoto Island, immediately east of Auckland City, is the youngest and largest of the region’s volcanic cones. Māori living there witnessed its formation. From radiocarbon and other dating methods, the eruption has been dated around 1400 AD. On nearby Motutapu Island, ash from Rangitoto was found lying above stone tools used for hunting and fishing, and the footprints of adults and children were found within the ash.
Mt Taranaki (Mt Egmont)
On the slopes of Mt Taranaki, Māori umu (ovens made of stones in a hollow) lie between ash deposits from eruptions around 1450, 1500 and 1655, indicating that people were travelling through Taranaki’s forests before 1450. According to Māori oral history Karakatonga pā, on the northern side of the mountain, was destroyed when the volcano erupted. The first Pākehā settlers did not realise that Taranaki was recently active, until in 1883 a local settler, A. W. Burrell, discovered pumice lodged in the forks of large mataī trees near the mountain.
In the mid-1800s Captain Byron Drury, in the Pandora, carried out a hydrographic survey around White Island. He described the crater:
‘[I]n the centre is a boiling spring about 100 yards in circumference, sending volumes of steam full 2,000 feet high in calm weather; round the edges of the crater are numerous small geysers, sounding like so many high-pressure engines, and emitting steam with such velocity that a stone thrown into the vortex would immediately be shot into the air.’ 1
White Island (Whakaari)
White Island (Whakaari) is New Zealand’s most active volcano, constantly venting steam and gases, blasting out new small vents, and intermittently discharging clouds of ash. The island is a feature of Māori traditions, and has probably been active since the ancestors of Māori arrived.
In 1820 the missionary Samuel Marsden, standing on a Tauranga hilltop, saw ‘immense columns of smoke’ from White Island. However, because the volcano is 48 kilometres off the Bay of Plenty coast its effect on the mainland has been minor, mostly infrequent dustings of ash. White Island is one of the few privately owned volcanoes in the world, and more than 10,000 tourists visit by boat or helicopter each year. The island’s abundant sulfur deposits were once mined, until a collapsing crater wall killed 11 miners in 1914.