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Natural hazards – overview

by  Eileen McSaveney and Simon Nathan

Earthquakes, volcanic eruptions, floods and landslides are part of life in New Zealand. They have shaped the country’s beautiful landscape, but also caused devastation and loss of life.


Living dangerously

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.

Earthquakes

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.

Volcanoes

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

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.

Under pressure

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.

Landslides

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.

Footnotes
    • Resilient New Zealand – A Aotearoa manahau: national civil defence emergency management strategy – 2003–2006. Wellington: Ministry of Civil Defence & Emergency Management, 2004, p. 2. › Back

Civil defence – coping with emergencies

Self-reliant communities

In the early days of New Zealand settlement, communities were isolated – when disaster struck they had to cope on their own. Today, earthquakes, floods and volcanic eruptions can cut communications, close roads and railway lines, and shut airports. Communities cannot assume that other people will be able to come to their rescue in an emergency. Self-reliance is still a major goal of civil defence.

The 1991 Resource Management Act made local authorities responsible for handling natural hazards in their area. Because there are 86 local authorities, the 2002 Civil Defence Emergency Management Act requires neighbouring regions to pool civil defence resources. For large-scale disasters the Ministry of Civil Defence and Emergency Management co-ordinates national assistance.

Goals of emergency management

The goals of local emergency management in New Zealand are sometimes summed up as the four Rs: reduction, readiness, response and recovery.

  • Reduction – local authorities must analyse potential hazards in their region and take steps to reduce the risk of injury and death, damage, and social and economic disruption.
  • Readiness – staff in local emergency services must be trained to deal with dangers, and the general public made aware of ways to stay safe during emergencies and how to cope on their own.
  • Response – actions taken before, during and after a disaster to save lives and property include declaring a civil defence emergency, evacuating areas, closing roads, and requisitioning anything useful. Local authorities can impose night-time curfews to prevent looting, and they have priority on communication networks.
  • Recovery – activities taken to restore the community to normal functioning. Many authorities encourage local businesses to plan recovery actions.

National civil defence

The 1929 Murchison and 1931 Napier earthquakes made the country aware of the need for a national organisation to assist during major emergencies. The 1932 Public Safety Conservation Act, passed after riots had occurred in major cities, allowed the government to declare a state of emergency when public safety or public order was likely to be threatened. There were no provisions, however, for organisations to plan for disasters.

The Emergency Precautions Scheme was set up in the shadow of the Second World War. Volunteers were organised and trained to deal with air raids, fires, poison-gas attacks and earthquakes. Interest in civil defence diminished after the Second World War, but was renewed with fears of nuclear war.

Ministry of Civil Defence

The Ministry of Civil Defence was set up in 1959, and by the mid-1960s the ministry’s focus was on natural-hazard emergencies.

In 1999, it became the Ministry of Civil Defence and Emergency Management, to reflect a new emphasis on making preparations to lessen the effects of a disaster. The ministry works with central and local governments, emergency services, and the utilities that maintain services such as water, power, gas, transport and telecommunications.

During local civil defence emergencies, the ministry has a National Crisis Management Centre that assists communities with expert advice and transmits information to government and local agencies. In the event of a nationwide emergency, it can manage the entire response.

The centre is designed to function in the event of a major earthquake or power failure – it has earthquake protection, emergency power, a water supply, air-filtering equipment, and computer and telecommunications systems. It is fully equipped with a cafeteria, sleeping accommodation, and first aid and other facilities for staff, and it is kept in a continuous state of readiness.


Being prepared

In legal language an ‘act of God’ is an extraordinary natural event that cannot be foreseen or prevented. In New Zealand, however, hazards such as floods, earthquakes and volcanic activity are not unforeseen – they are inevitable. These hazards are constantly monitored, and communities are making preparations to lessen the dangers and damaging effects.

Avoiding dangers

Flooding is the main cause of civil defence emergencies in New Zealand. Thousands of kilometres of stopbanks have been built to keep high flows within the river channels. Local authorities can regulate land use and restrict building construction in flood-prone areas.

The illusion of security provided by stopbanks, however, has often encouraged the dense settlement of riverside areas. For example, the Hutt Valley (north of Wellington city) remained sparsely settled until extensive stopbanks were built along the Hutt River in the early 1900s. In New Zealand towns and cities, thousands of people and much valuable property are now at risk from the rare floods big enough to breach the protection.

Earthquakes can’t be avoided, but local authorities can determine areas where shaking will be most severe, and prohibit building directly over active fault lines. They can also prohibit building in areas where landslides are likely.

Building for safety

The collapse of built structures during disasters often presents the greatest dangers. New Zealand has a building code with specific safety objectives. For example, a building must be able to withstand the forces exerted by earthquake shaking or by maximum wind gusts likely in the region. If people wish to build in a flood-prone area, the lowest habitable floor must be high enough that water will not enter the building in the event of a 1-in-50-year flood.

Other structures such as bridges and overpasses, and utility pipelines and towers, must be designed to withstand extreme events. New Zealand is recognised internationally for its research into the behaviour of concrete structures during earthquakes. Many New Zealand buildings and bridges are protected against earthquakes by lead dampers and lead and rubber bearings invented by New Zealander Bill Robinson.

On your own

The Ministry of Civil Defence and Emergency Management recommends that all people have a survival kit with enough water and food to last for three days, a battery-operated radio, torches, a first-aid kit, and other supplies. Information about how to prepare for emergencies, reduce the chances of being hurt and what to do after the worst has passed is listed in the back of the telephone book.

Warnings

Both national and local agencies provide hazard warnings. Weather forecasters broadcast warnings of possible severe weather. Local authorities maintain automated instruments to measure rainfall, and river and lake levels within their regions. Using this information they issue flood warnings.

New Zealand has a national network of instruments and data centres, called GeoNet, operated by GNS Science. This service detects and analyses earthquakes, and monitors volcanic activity and large landslides. Warnings of tsunamis are received from the Pacific Tsunami Warning Center in Hawaii.

Natural-disaster insurance

New Zealand is one of the few countries in the world with government-managed natural-disaster insurance for homes and the land beneath them, and personal possessions. Earthquake Commission (EQC) insurance covers homes up to a limit of $100,000, and personal possessions up to $20,000, with some compensation for damage to land under or close to a residence.

The cover includes damage from earthquakes, landslides, tsunamis, volcanic eruptions, hydrothermal activity, and fires resulting from these disasters. Private insurance, however, is needed for storm and flood damage to homes. EQC insurance does not cover commercial properties or vehicles.


Hononga, rauemi nō waho

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How to cite this page: Eileen McSaveney and Simon Nathan, 'Natural hazards – overview', Te Ara - the Encyclopedia of New Zealand, http://www.TeAra.govt.nz/mi/natural-hazards-overview/print (accessed 14 November 2019)

Story by Eileen McSaveney and Simon Nathan, published 12 Jun 2006