New Zealanders live in a beautiful but demanding land – the challenges of coping with its rugged mountains, powerful rivers and extremes of weather have helped forge the national character. The natural forces that create the country’s stunning scenery present many hazards, including earthquakes, volcanic eruptions, tsunamis, storms, floods and landslides. Being prepared to deal with these dangers and constructing our built environment to minimise their effects is the price of living in a dynamic landscape.
A surprising number of hazards can be linked to New Zealand’s location. It lies in a geologically unstable zone, straddling two moving sections of the earth’s crust – the Pacific and Australian plates. Ninety-five per cent of New Zealanders live within 200 kilometres of the boundary where the plates meet.
The worst disaster
Although the Hawke’s Bay earthquake (258 dead) is often cited as New Zealand’s worst disaster in terms of loss of life, this is only true for events on New Zealand soil.
The largest death toll in a single day was during the First World War battle of Passchendaele, 12 October 1917, when 843 men from the New Zealand Division were killed in a few hours.
Under relentless pressure, the country is shaken daily by earthquakes. Most are imperceptible, but up to 200 each year are big enough to be felt, and a few have caused major damage and many fatalities. The heaviest toll was in 1931, when 258 people died in the earthquake that struck the Napier–Hastings region. Since then, however, very few people have been killed in earthquakes in New Zealand.
New Zealand has many active and dormant volcanoes, and the largest city, Auckland, is built on a volcanic field. The most destructive eruption in historic times, of Mt Tarawera in 1886, killed at least 120 people. The volcanoes of Tongariro National Park have erupted dozens of times in the past two centuries. This has spread volcanic ash that has disrupted travel. However, the ash has also increased the fertility of the region’s soils.
The same magma (molten rock) that feeds the volcanoes powers the geysers, hot springs, and mud pools of New Zealand’s geothermal areas. Thousands of tourists safely view these wonders each year, but some deaths have occurred when their potential dangers have been taken too lightly.
Tsunamis are generated by movements of the sea floor during earthquakes, by volcanic eruptions and by landslides. Offshore earthquakes in New Zealand have produced tsunamis up to 10 metres high. Tsunamis from other parts of the Pacific have also hit our coasts. Only one death from a tsunami has been recorded since European settlement, but Māori tradition indicates earlier deaths.
A hazardous climate
New Zealand lies in the path of the roaring forties weather systems. The mountainous terrain often increases the rainfall produced by frontal storms and tropical cyclones. Flooding, due to intense or prolonged rain, is by far the most frequent and costly disaster in New Zealand.
New Zealand’s rugged land also affects the winds – they pick up speed as they are funnelled over mountains and through Cook Strait. Mountain huts have been blown off ridges, train carriages off their tracks, and vast areas of forest plantations have been flattened. Tornadoes are not common, but some have proved deadly. In 1948 a tornado wrecked 150 houses and killed three people in Hamilton.
Sir Geoffrey Palmer, a former prime minister of New Zealand said:
‘Sometimes it does us a power of good to remind ourselves that we live … where two tectonic plates meet, in a somewhat lonely stretch of windswept ocean just above the roaring forties. If you want drama – you’ve come to the right place.’ 1
Rapidly changing weather, including snow and freezing temperatures, have killed many in the mountains, including dozens of ill-equipped miners during the gold rushes of the 1860s.
New Zealand’s uplifted land is rapidly eroding, creating deep valleys with hillsides that are prone to collapse. Many landslides are triggered by heavy rain or earthquakes. In 1979, part of the Dunedin hillside suburb of Abbotsford gave way due to unstable rock layers under the area. This wrecked 69 homes.