Home on the Range
Empress Hut, perched on the western flank of Mt Cook, is one of more than 1000 huts peppered throughout the New Zealand back country. But how secure is this heritage in the face of difficult economic times?
Empress Hut, perched on the western flank of Mt Cook, is one of more than 1000 huts peppered throughout the New Zealand back country. But how secure is this heritage in the face of difficult economic times?
A tsunami hit New Zealand on June 23, 2001. Gauges in the Chatham Islands detected a sudden 55 cm rise in sea level, and several hours later mainland New Zealand recorders noted a 30 cm rise. Warnings had been transmitted from the Pacific Tsunami Warning Centre in Hawaii, so New Zealand seismologists knew the wave was coming and were prepared. The tsunami was triggered by a distant earthquake near Arequipa, on the coast of Peru. It was plate business, as usual, at a depth of 40 km within the subduction zone where the oceanic crust of the small but fast-moving Nazca Plate (east of the Pacific Plate) is drawn down beneath the thick continental crust of the South American Plate. This event was the biggest earthquake the world has seen in the past 25 years. At magnitude 8.3, it can rightly be described as a "great" earthquake. It ruptured a length of seafloor some 300 km long parallel to the coast and more than 100 km offshore. The tsunami it generated, travelling at 700 km/h, took just 15 minutes to reach the Peruvian coast. It arrived in the Chathams 14 hours later. Amazingly, the earthquake and tsunami claimed fewer than 150 lives. Had they struck on a summer's day when that section of 5 coast was packed with beachgoers, the casualty total would have been much greater. We do not hear of tsunami in New Zealand very often, but they do constitute a major hazard. Historic tallies of tsunami deaths for New Zealand are comparable to total deaths from earthquakes within the past 200 years: between 200 and 300 lives. At least six significant tsunami have hit New Zealand in this time period. There is a record of several hundred Maori being killed by a huge wave in Fiordland in 1826, and of a Chatham Islander being drowned in a tsunami that struck Kaingaroa (on the north coast of Chatham Island) in 1868, probably generated from the same undersea fault as the recent event. Tsunami are triggered by sudden massive displacements within ocean water masses such as are caused by earthquakes, volcanoes and landslides, especially submarine landslides. The deadliest tsunami are those triggered locally, for which there is little or no warning and no time to escape. The tsunami generated by the Arequipa earthquake, for example, was 12-15 m high. As it romped inland, traversing up to a kilometre of flat land on the coastal plains nearest the epicentre, it destroyed virtually everything in its path. Earthquakes and tsunami are rude monsters that raise their ugly heads at will, it seems. What can be done about them? The old Maori story of the boy and the taniwha says it all. The boy asks his grandfather: "How can I fight the taniwha?" The old man replies: " First, get to know the taniwha." New Zealand scientists and engineers are doing just that: getting to know tsunami. They are visiting places which have been struck by tsunami, such as Sissano Lagoon, Papua New Guinea, which suffered a massive tsunami in July 1998, and now the Arequipa coast in Peru. The risk to humans from hazards such as earthquakes and tsunami grows daily as humanity spreads its infrastructure over the Earth's surface. Recall the horrors of the 1999 Izmit earthquake in Turkey: more than 20,000 lives lost. Or the 1995 Kobe earthquake, with more than 5000 dead. The impact of the Kobe earthquake has been likened to the New York Twin Towers disaster. Certainly, a similar number of lives were lost. Arequipa was a subduction-zone earthquake. Although we have such earthquakes in New Zealand, there have not been any major ones in historic memory. This is a significant difference between New Zealand and Peru: they have had them, we haven't ... yet! There is another difference of a geological nature between the two countries. The Earth's crust where New Zealand is situated is thinner than under Peru. Ours is 25 km thick, compared with their 40 km-plus. So, because we are more "thin-skinned," the land surface is that much closer to the subduction zone—where the Pacific Plate grinds beneath the Australian Plate. Should there be a major earthquake within that subduction zone, the intensity will he much greater than that of a Peruvian event, and hence more damage will be done. New Zealand's current systems for monitoring such hazards are based on old technology, with old instruments that are sparse and expensive to maintain. But with substantial funding from the Earthquake Commission announced in March 2001, the Institute of Geological and Nuclear Sciences (GNS) is modernising surveillance equipment for monitoring New Zealand's non-biological natural hazards, namely earthquakes, volcanoes, landslides, geothermal activity and tsunami. These new instruments will be managed and maintained as an integrated system called GeoNet and based at GNS in Gracefield, Lower Hutt. GeoNet will greatly improve hazard monitoring, forecasting, disaster-management response and disaster recovery. As an adjunct to GeoNet, an educational programme designed as a resource for schools has been launched. "Quake Trackers" was produced in 1998 by GNS and Victoria University to improve science education and earthquake-hazard awareness in secondary schools. To date, 14 high schools have Quake Trackers, and there is a flourishing website-based national school seismograph network which enables students to develop skills in computer science, earth science, physics and seismology.
The silken web is as much a signature of spiders as are eight legs and an abundance of eyes. When we wrote about all things arachnid in the 10th issue of New Zealand Geographic, we noted that the silk which spiders spin is much more elastic than nylon, and that it has been considered a material with great potential. The matter of supply was the only difficulty. In the decade that has elapsed since that article was published, what more have we learned about spider silk? Is mass production any closer—or even desirable?
A fungus responsible for decimating amphibian populations around the world has struck one of New Zealand's rare native frogs. Researchers working in the Coromandel Range have found a dead Archey's frog with skin lesions, suggesting that it died from a chytrid fungal infection caused by Batrachochytrium dendrobatidis. Chytrid fungi are found mainly in fresh water, but the group has estuarine and soil-dwelling representatives as well. Some species live in the guts of herbivores and some are parasites and saprophytes of algae, plants, nematodes, insects and even other chytrids B. dendrobatidis is the only species known to parasitise vertebrates. It infects an animal's epidermal cells, causing a thickening of the outer layer of the skin, but it is not known how that change leads to death. Globally, two amphibian orders, the Anura and Caudata, comprising 14 families and 93 species, are known to be infected by this fungus. Diseased species have been found in Africa, South America, Central America, North America, Europe, Australia, and now Oceania. The first record was from North America in 1974. Australia, where the fungus arrived in 1978, has been the hardest hit, with 46 species affected, including eight listed as endangered and five as vulnerable. The fungus was first found in New Zealand in 1999 in two well-established Australian species, the southern bell frog and the green and golden bell frog. Archey's frog is found only in the Moehau and Colville Ranges on the Coromandel Peninsula and at Whareorino Forest west of Te Kuiti. The species was in decline even before this current fungal problem was discovered. "Frog populations have been decreasing worldwide since the 1980s, and New Zealand is unfortunately following the global trend," says Department of Conservation officer Andrew Harrison. "Chytrid fungus has the potential to decimate New Zealand frogs if it spreads." He said that more information was required on the fungus, particularly its method of transfer from introduced frogs to native species. Other research is centred on detecting the fungus in water and on vegetation. Harrison says New Zealand's leiopelmid frogs are "of huge scientific interest internationally, as they are the most ancient frogs left on the planet, survivors of the Jurassic period some 200 million years ago." Because the fungus is a possible biosecurity issue, a technical advisory group to the Ministry of Agriculture has been set up. Victoria University researcher Ben Bell, a member of the group, says, "The next step is to survey the extent of population decline and to find out if the survivors have been infected." The group is anxious to stop the fungus spreading to New Zealand's other three native species, particularly Hochstetter's frog, which shares native forest habitat with Archey's frog. Bell says the group is considering moving some frogs to a safe facility where they may be bred in captivity. Meanwhile, Department of Conservation workers are taking strict precautions when visiting frog habitats to try to minimise the spread of the fungus. Harrison said an infected frog would appear emaciated and lethargic, often with abnormalities of the skin or eyes. "The fungus infects the skin of frogs. We're not yet sure whether it suffocates them or kills them as they absorb the toxins released by the fungus." While some funding has been directed at chytrid research in the United States and Australia, many questions remain unanswered. For instance, no one knows why the fungus, which belongs to a group that has been in existence for 550 million years, has suddenly come to be toxic to frogs and tadpoles. One theory speculates that the pathogen is a mutated form. Other researchers suggest that climate change, such as drier conditions, are causing amphibians to crowd together at water sources, helping the fungus to spread. Other factors have been blamed for some frog die-offs, such as uncontrolled chemical use. But nearly half the dead frogs handed in during a three-year Australian survey were diagnosed with chytridiomycosis, showing no other disease and no evidence of depressed immunity. Chytridiomycosis has recently been reported in amphibians collected for the global pet trade. Given that 180,000 animals of at least 21 endangered European species were imported into the UK alone between 1981 and 1990, there is huge potential for chytrid infection to spread still further.
The two lows that crossed central New Zealand in the second week of October brought much-needed rain to many areas suffering from drought. Blenheim Airport received 94 mm of rain over six days, when the average for October is only 66 mm. In September, Blenheim Airport had just 11 mm of rain—the third-lowest September rainfall on record. In fact, September was the driest on record in many places in the south-west of the North Island, including Wanganui, Palmerston North Airport, Levin, Paraparaumu Airport and Wellington Airport. All these places received good rain from the early October storms, most getting more than the monthly average. Among the unusual side effects of the rain was the discovery of some fossils on a farm near Otaki. The farmer, Barry Mansell, had found a large fossilised shell in the Otaki Gorge area around 40 years ago, so when he came across a fresh slip on the road he tried his luck again. After five minutes searching he found half a dozen rocks containing fossil shells the size of scallops. Of course, the storms were not entirely beneficial. Some roofs were lifted in Wellington and a few trees came down, cutting power lines here and there. The Cook Strait ferries stopped sailing, and wet roads contributed to a spate of accidents. But on the whole the storms were a blessing for the rain they brought. How far ahead can forecasters see such rain-bearing lows coming our way? The global computer models that are one of the mainstays of modern forecasting are now very good out to two or three days into the future and useful out to four or five days ahead. But by five days ahead the computer predictions of the locations of low centres can be in error by 1000 km, and the intensity of a low can be out by 30 hPa. These errors come from inaccuracies in the initial measurement of weather conditions for the start of a computer model's run, as well as approximations in the equations used to describe atmospheric processes. Initially, errors grow in a linear fashion, so that after two days the errors are twice as big as after one day. But after more time has elapsed the errors tend to grow much faster, in a non-linear fashion. For example, a small error in the measurement of wind speed and direction in the jet-stream at 10 km above the Tasman Sea can affect whether a computer model deepens a low or not. If the low is deepened, it will change the structure of the jet-stream in a way that further enhances the deepening of the low for a period of 12 hours or so. If the computer model triggers a feedback process like this, it will quickly send its predictions down the wrong path. Equally, if the computer model misses such a development it will also end up way off track. Lack of observations to correctly describe the initial state of the atmosphere at the start of a computer run has always been a major problem in the southern hemisphere. Much of New Zealand's weather comes from over the southern Indian Ocean and the seas south of Australia, where there are almost no conventional observations—just a ship report now and again, plus a handful of drifting buoys and the weather station on Kerguelen Island, more than 3000 km southwest of Perth. This observation gap has diminished significantly in recent years as more sophisticated observing instruments have been put on the newer weather satellites. Some of these measure upper-level winds by tracking the movement of high clouds. Others measure surface wind speeds by measuring capillary waves on the ocean surface. Air temperature and humidity are measured more accurately and over a finer scale both vertically and horizontally than they used to be. The benefits of this flood of new measurements have been seen in improvements to the five-day forecasts over the past decade, but the problem of rapid error growth in the models remains beyond about five days. Consequently, researchers have been working on a new way to handle the problem of error growth, known as ensemble forecasting. Making use of the tremendous power of newer computers to handle millions of calculations in the blink of an eye, researchers now run a computer model many times for the same situation, using slightly different initial conditions for each run. The variations in initial conditions are all in agreement with the observations but represent different possibilities in the initial atmospheric conditions, given the uncertainties between the points for which there are observations. There are two tactics involved in choosing the range of variations in the initial conditions for the different model runs. One is to have the most variations over data-sparse areas, such as the Indian Ocean, while the other is to concentrate the variations around an important weather system such as a developing low-pressure centre or jet-stream, wherever they happen to be on the day. Once the computer has completed all the runs, the results can be compared. If over one area, such as New Zealand, they produce a similar pattern of isobars, meteorologists can have high confidence in the result. If, instead, the weather patterns are widely different, we have low confidence in the forecast. One way to present the ensemble results is known as a spaghetti diagram, where the same one or two isobars are plotted from each of the model runs. An example of a spaghetti diagram, of the 500 hPa map for midday on October 10, appears on page 8. Twenty-three different model runs are shown, each based on an analysis time of midday October 4 and run for six days ahead. The point to note from this example is how much spread there is in the lines from about South America around to western Australia, in contrast to lines in the Tasman Sea—New Zealand area, which are quite close together. Closely spaced lines indicate that there is considerable agreement in all model runs that there will be a large trough of low pressure over New Zealand. The widely spaced lines in the area from South America to Australia indicate much more uncertainty as to what will happen there. The amount of variation between individual runs in an ensemble can be used to give a measure of confidence in the forecast and to derive a percentage probability of say 1 mm of rain or 10 mm of rain for a particular region. Another way to present the ensemble runs is to average the results. This has been done with the surface isobars for midday October 10, shown above left, using 23 model runs out to 15 days based on a start time of midday September 25. A trough of low pressure is indicated over New Zealand and the Tasman Sea, but seems not to be intense, as it is delineated by only a single isobar. By contrast, the analysis of what actually happened on the day, shown above right, has five isobars around the trough over New Zealand. This is typical of the problems the forecaster faces when considering the ensemble products, as deep lows 10 days or more ahead will always be "blurred" to look like shallow features. Ensemble forecasts can also be run at very high resolution over much shorter time periods. In the United States, research is going on to try to use ensembles to forecast the individual thunderstorms that give rise to tornadoes. Ensembles do not necessarily involve computers. The forecast for the Allies' D-Day landing in France in June 1944 (see New Zealand Geographic, Issue 22) was the work of three independent forecasting teams. One team was from the British Meteorological Office, another from the Royal Navy, and the third from the United States Army Air Force. Their results were then coordinated via a conference call, and a single forecast agreed on. The best ideas have often been around for a long time!
Last century, hope of a better life drew many Irish, among them a strong contingent of Catholics, to New Zealand, and the religion they brought has taken root and flourished here, becoming a pillar of New Zealand society. Catholics are the second most numerous Christian group in this country, and if present trends continue, before long they will be the major group. Despite their abundance, Catholics have often been at odds with the establishment, and religious icons have not been the only aspect of Catholic belief and practice to perplex outsiders.
Despite being hunted to the edge of extinction in the 19th century, New Zealand fur seals seem to be making a modest recovery. Although the animals are still sparse around most of the North Island, several South Island rookeries are increasing in size, making some fishers nervous at the prospect of increasing competition from these efficient predators. Many, however, are entranced by the lithe, playful animals-and regard seals as a great asset to our coastal wildlife.
Ten years have elapsed since a successful and pervasive road-safety campaign began in New Zealand—not on television or radio or in the press, but by the side of the road.
Gypsies, tramps and thieves—in some measure, New Zealand's swaggers were all of these things. They were opportunists in a society that idolised hard work and conformity. Their vagabondage earned them few friends and little respect, but—like our cheeky alpine parrot—they added a dash of colour to rural life.
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