Lifestyle and Leisure
Earthquakes in New Zealand?
Before choosing a place to live many Brits often ask, is there anywhere in New Zealand not at risk of earthquakes, writes Maike van de Heide?
To put it simply the answer is no. New Zealand is one of the most active seismic places on earth. The country lies on the active boundary of the Pacific and Australian tectonic plates and as a result, earthquakes are a common feature of Kiwi life: there are some 10,000 to 15,000 earthquakes each year, of which 100 to 150 are felt by people.
Kiwi Faultlines
As devastating as an earthquake can be to humans, New Zealand has this natural phenomenon to thank for much of its natural beauty and geological features, such as the Southern Alps which have been largely shaped by the Alpine Fault.
The Alpine Fault produces some of New Zealand's biggest earthquakes but luckily, most of the directly affected area is entirely unpopulated. This fault is 600 kilometres in length and over the past 900 years it has produced about four magnitude eight earthquakes, with the most recent one occurring in 1717.
While the last major quake from the Alpine Fault was a very long time ago indeed, the fault is still restless and moves horizontally at about 30 metres per year, which is quite speedy by global standards. Because of this, scientists say there is a high possibility that this fault will make its presence known within the next 40 years, which could produce one of the biggest earthquakes since European settlement of New Zealand. Now there's something to look forward to! Other historically active seismic areas include Nelson and Westland, the Taupo Volcanic Zone in the central North Island and Wellington, which is the biggest urban area on an active fault.
A shaky history
Much of New Zealand's history is defined by the large earthquakes that have rearranged both land and cities. Between 1929 and 1934 New Zealand was hit by five major earthquakes of magnitude seven or more.
Napier, for instance, was only rebuilt in its famous art deco style after the city was flattened in the biggest earthquake since instrumental recording began. The magnitude 7.8 shake killed 261 people and left Napier unrecognisable.
The Murchison and Inangahua areas, southwest of Nelson, still bear the scars of the 7.8 and 7.1 shakes of 1929 and 1968 respectively. Travelling along the Murchison to Westport road, you will see signs pointing to the earthy scar of a massive landslide which is still visible today. Not too far away, the gushing ten metre-high Maruia Falls, just south of Murchison, was formed during the 1929 earthquake which redirected the river over the edge of one of its old channels.
Wellington has the massive 1855 Wairarapa earthquake, the biggest known in New Zealand, to thank for much of the land that now supports the central city. About 5,000 square kilometres of land was raised up during the 8.2 quake, and more land has been reclaimed since. You will find markings of the original shoreline as it was in 1840 on Lambton Quay which, like several other quays, is now nowhere near the waterfront.
Recent quakes
While tremors shake parts of New Zealand on a regular basis, one of the most surprising recent quake was a cluster of tremors near Auckland.
Generally not seen as a hot-spot for quakes, Aucklanders, and especially seismologists, were very interested when small tremors measuring 2.5 and 3.3 on the Richter scale were felt on Waiheke Island and the North shore suburb of Devonport. The shallow quakes, which were centred some 30 kilometres east of Auckland, were described by experts as quite rare but not as a sign that the area's volcanic field was reawakening.
Early in 2005, the Bay of Plenty was also hit by several 'swarms' of minor tremors, which caused damage to homes and property. One woman was killed when several earthquakes caused an unstable tree to fall on three cars. But, as Kiwis will tell you, they would rather have a whole lot of small quakes than one huge shake.
Last year's largest earthquake was a magnitude six shake near Haast on the South Island's West Coast. It was followed five minutes later by another earthquake of 5.7 in the same area. There was limited damage reported in the sparsely populated area. The region suffered a similar earthquake in December 2001.
Records dating from the 1840s show that, on average, New Zealand can expect several magnitude six earthquakes every year, one magnitude seven every ten years, and an eight every century. But large earthquakes are not evenly spaced, and New Zealand has been hit by several potentially major earthquakes in the last three to four years. According to the Institute of Geological and Nuclear Sciences, shallow earthquakes (less than 30 kilometres deep) above magnitude 5.0 are capable of producing significant damage and casualties in built-up areas.
In August 2001, a 7.0 earthquake centred 420 kilometres offshore from Gisborne was felt as far south as Christchurch and caused minor damage and a brief power cut north of Gisborne. The sparsely populated region of Fiordland was shaken by a shallow 7.1 quake in August 2003. Luckily, because the epicentre was not anywhere near human activity, no lives were endangered and damage was limited to jam jars falling off supermarket shelves in areas of Otago and Southland.
In November 2004, a shallow 7.2 quake occurred offshore south of Invercargill, which again caused no notable damage to humans or property despite being felt in Palmerston and New Plymouth.
Be prepared
While the prospect of the 'big one' hitting anytime soon is not something that Kiwis like to think about too often, it is wise to be prepared for the eventuality.
New Zealand school children have earthquake drills, where they are taught to climb under a desk or stand in a doorway if the ground starts to shake. This is something that should also be encouraged at home. It is important to keep away from windows, any hanging lights and it often pays to secure heavy items or put them near floor level. Heavy furniture which could fall should also be secured to the floor or wall.
Put strong catches on your cupboard doors, secure your hot water cylinder and check that your chimney is secure. Households are also encouraged to have a survival kit handy with a first-aid kit and manual, a torch, radio and batteries, candles and matches, enough cans of food and bottled water for five days, a can opener, plastic rubbish bags, a change of clothes, a primus stove and personal medication or other needs. You could also include important family documents.
If you do experience an earthquake, you should take cover and stay indoors until the shaking stops. If you are outdoors, get away from trees, buildings and power lines. Always remember that there could be aftershocks which can occur straight after the main tremor. These can go on for weeks or even months. Turn on the radio and listen for instructions from Civil Defence.
Read another article about New Zealand:
Earthquake hits Wellington
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