Hazards

Earthquakes


Canterbury lies across the boundary of the Australian and Pacific tectonic plates. As a result, we live in an active landscape where earthquakes are common. Earthquakes make the ground shake, and can also cause fault movement at the ground surface, landslides and liquefaction (where the ground becomes like jelly), and sometimes tsunamis. Canterbury has many earthquake faults, particularly in the hills and mountains of the Southern Alps and North Canterbury.nbsp; Earthquakes are more likely in these areas, and less likely along the Canterbury Plains and South Canterbury. The 2010/2011 earthquakes happened on hidden faults under the Canterbury Plains that don't move very often, perhaps once every several thousand years. Damaging earthquakes have occurred in Canterbury in 1869, 1870, 1881, 1888, 1901, 1922, 1929, 1946, 1994, 1995, 2010 and 2011.

 

Links:

ECan earthquake information www.ecan.govt.nz/earthquakes

GNS Science www.gns.cri.nz/Home/Learning/Science-Topics/Earthquakes

GeoNet www.geonet.org.nz

Te Ara Encyclopedia of New Zealand http://www.teara.govt.nz/en/earthquakes 

Canterbury Maps information on liquefaction in Greater Christchurch http://canterburymaps.co.nz/Viewer/#webmap=e47bcfe622f146328b222d8ac12114f9 

Canterbury Maps information on ground shaking map http://canterburymaps.co.nz/Viewer/#webmap=aea81608b45f401db8e10d2ce5e339a2  

Tsunami


The whole of the Canterbury coastline is exposed to tsunamis that come from across the Pacific Ocean (distant-source tsunamis). These tsunamis take many hours to travel from where they start, and we have time to give an official warning. All of the significant tsunamis to affect Canterbury in 1868, 1877, 1960 and 2010 have been distant-source tsunamis that started near South America. The most vulnerable areas to distant-source tsunamis are Pegasus Bay and Banks Peninsula, because of the shape of the sea floor and land in those areas. Some parts of the North Canterbury and Kaikoura coasts are exposed to tsunamis that start closer to shore (local and regional-source tsunamis). These tsunamis take less than three hours, and sometimes only a few minutes, to travel from where they start to the coast, not enough time to give much, if any, official warning.There have been no confirmed local-source tsunamis in Canterbury since European settlement. Tsunamis are usually caused by underwater earthquakes, but can also be caused by underwater landslides and volcanoes.

 

Links:

 

 

Canterbury maps story board on tsunami  http://canterburymaps.govt.nz/webapps/CanterburyHazards/Tsunami_Canterbury.html

ECan tsunami information www.ecan.govt.nz/tsunami

NIWA www.niwa.co.nz/natural-hazards/hazards/tsunami

GNS Science gns.cri.nz/index.php/gns/Home/Our-Science/Natural-Hazards/Tsunami

GeoNet www.geonet.org.nz/tsunaminbsp;

Te Ara Encyclopedia of New Zealand www.teara.govt.nz/en/tsunamis

 

 

Pandemic


An epidemic is when many people have the same disease at the same time. A pandemic occurs when an epidemic spreads between many countries. A new type of influenza or the flu, is the most likely disease to cause a pandemic.Influenza pandemics have affected New Zealand in 1918/19 (when around 8600 people died), in 1957/58 and 1968/69. A pandemic could have a large impact on Canterbury because many people would be sick at the same time, and people would need to stay away from each other to help stop the flu virus spreading. This means people would not be able to go about their daily lives normally, and emergency services and essential services such as power and telecommunications and food distribution would be unable to operate properly. There would also be little help from outside Canterbury as the rest of New Zealand would be affected as well.

 

Links:

 

Ministry of Health pandemic planning and response; www.health.govt.nz/our-work/emergency-management/pandemic-planning-and-response

Environmental Science and Research Virological Surveillance; www.surv.esr.cri.nz/virology/virology.php

World Health Organisation www.who.int/influenza/en/

Te Ara Encyclopedia of New Zealand; www.teara.govt.nz/en/epidemicsnbsp;

1918 Influenza Pandemic; www.nzhistory.net.nz/culture/influenza-pandemic

Ministry of Health information on ebola; http://www.health.govt.nz/your-health/conditions-and-treatments/diseases-and-illnesses/ebola-information-public 

Flooding


Flooding is the most common hazard experienced in Canterbury and damaging floods have affected many areas in Canterbury in the last 150 years. Floods in the alpine rivers that flow from the Southern Alps, the Waiau, Hurunui, Waimakariri, Rakaia, South Ashburton, Rangitata, and Waitaki rivers are generally caused by north-westerly rain that falls in the mountains. Rivers that start in the foothills or on the plains the Clarence, Kowhai, Conway, Waipara, Ashley, Styx, Avon, Heathcote, Halswell, Selwyn, North Ashburton, Hinds, Orari, Waihi, Temuka, Opihi, Pareora, and Waihao rivers can flood during heavy rain from the south-east or south-west. Alpine and foothills/plains rivers do not usually flood at the same time. Heavy rain along the lower Canterbury Plains can cause flooding of smaller streams or ponding of water in low lying areas. Sea water flooding in coastal areas can happen when high tides, certain weather systems, and large sea swells combine to drive the sea up and over the beach and onto the land behind.

 

Links:

ECan flood information; http://www.ecan.govt.nz/advice/emergencies-and-hazard/flooding/Pages/default.aspx

NIWA river flooding; www.niwa.co.nz/natural-hazards/hazards/floods

NIWA coastal flooding; www.niwa.co.nz/natural-hazards/hazards/coastal-storm-inundationnbsp;

Te Ara Encyclopedia of New Zealand; www.teara.govt.nz/en/floods

Ministry of Health information on ebola; http://www.health.govt.nz/your-health/conditions-and-treatments/diseases-and-illnesses/ebola-information-publicnbsp;

Snow


Winter snow fall is common above 1,000 m in the Southern Alps. Heavy snow falls below 1,000 m in Canterbury are less common, affecting mostly rural areas and alpine roads. Significant snow falls occur at sea level every few years in Canterbury. Heavy snow storms can disrupt electricity and telecommunications, as lines collapse under the weight of snow, and they can disrupt road, rail and air transport. Very occasionally, buildings are damaged or collapse from the weight of snow. Snow storms, particularly in early spring during lambing, can result in stock losses through cold or lack of feed. The risk to life from avalanches is low and is mainly restricted to skiers, trampers and mountaineers in the back country.

 

Links:

 

NIWA; www.niwa.co.nz/natural-hazards/hazards/snow-and-avalanches

Metservice warnings; www.metservice.com/warnings/home

 

Severe Weather


Severe weather includes heavy rain, strong winds, hail and snowstorms, and all four can affect Canterbury. Heavy rain in Canterbury is usually associated with southwesterly or southeasterly weather, and can cause flooding in rivers that start in the foothills or plains, along with ponding of rainwater in low-lying areas. Snowstorms can dump thick snow over large areas of Canterbury, which can affect transport, power and telecommunications. Hail is associated with thunderstorms and is generally localised ndash; damaging hailstorms are uncommon in Canterbury. Strong winds in Canterbury are usually caused by north-westerly conditions. When north-westerly winds hit the Southern Alps they are forced up, over and down onto the Canterbury Plains, creating strong turbulence and downstream winds. These down slopers windstorms can be very localised and do not usually bring rain, as most of rain falls on the windward side of the mountains. Canterbury is rarely affected by ex-tropical cyclones that sometimes hit the North Island.Canterbury's worst recent windstorm occurred in August 1975 when north-westerly wind gusts of up to 195 km/hr blew roofs of buildings, destroyed garages and sheds, damaged aircraft and blew over power lines. Thousands of trees were blown down or uprooted, including damage to 11,000 hectares of pine forest.

 

Links:

 

NIWA;- wind www.niwa.co.nz/natural-hazards/hazards/extreme-weather-winds-and-tornadoes

NIWA; heavy rain www.niwa.co.nz/natural-hazards/extreme-weather-heavy-rainfall

Te Ara Encyclopedia of New Zealand www.teara.govt.nz/en/weathernbsp;

Metservice warnings www.metservice.com/warnings/home

 

Fire


A wildfire is any unplanned fire in an open space, such as grassland or forest.People start most wildfires, either deliberately or by accident.The way wildfires spread depends on how much vegetation there is that can be burned, weather conditions (temperature, humidity and wind speed) and topography the steeper the slope, the faster the fire will advance. Wildfires are most common between November and March when conditions are generally drier and temperatures higher. Canterbury has one of the most severe fire climates in New Zealand, having hot, dry periods over summer and frequent warm, gusty north-westerly winds. Wildfires can damage forests, particularly pine plantations, and rural development including houses, farm buildings, fences and livestock. Risk to life from wildfire in Canterbury is low - fire fighters, forestry workers, rangers and trampers are most at risk.

 

Links:

 

National Rural Fire Authority; www.nrfa.org.nz

 

Drought


A drought happens when rainfall is lower than normal over an area for a long time, causing the soil to be dryer than usual. Grass and other plants cannot grow well, or at all, which means there is not enough food for production or for animals to eat. Droughts can be very complex in Canterbury. The north-westerly weather conditions that can cause low rainfall and dry soil on the Canterbury Plains, can at the same time cause high water levels in the alpine rivers that flow across the Plains. Water from these rivers, along with groundwater, is often relied on during dry periods and droughts to water pasture. Change in agricultural land use in Canterbury over the last 10 years, from sheep and beef farming to dairying, which requires more water, has increased this dependence on irrigation. Droughts can have significant social impacts on farming communities as difficult farm management decisions are made. Drought conditions also increase the chance of wildfire, particularly if the drought happens after a time of good growth that has produced a lot of vegetation.

 

Links:

 

NIWA; www.niwa.co.nz/natural-hazards/hazards/droughts

New Zealand drought monitor;  https://www.niwa.co.nz/climate/information-and-resources/drought 

DairyNZ information on drought; http://www.dairynz.co.nz/farm/adverse-events/drought/

Rural News on drought; http://www.ruralnewsgroup.co.nz/rural-news/trending/act-now-to-minimise-drought-losses 

Nathan Guy, Minister for Primary Industries visits Canterbury; http://www.radionz.co.nz/news/national/264096/close-watch-on-dry-spell-govt 

Canterbury Water Management Strategy; www.cwms.org.nz

 

 

Landslides


Many different types of landslide occur in Canterbury. Rockfalls and rock avalanches happen in the highly fractured rocks of the Southern Alps. They can be triggered by strong earthquakes, or can be simply the result of long-term natural erosion.The jointed volcanic rock of the Port Hills and Banks Peninsula is susceptible to rockfalls. Steep slopes or vertical rock faces are eroded and weathered and are particularly vulnerable to earthquake shaking - the 2010/11 Canterbury earthquakes caused many rockfalls in the Port Hills of Christchurch, damaging houses, roads and other infrastructure and killing six people. Thick wind-blown silt overlying the volcanic rock across Banks Peninsula are susceptible to rainfall-triggered shallow erosion and collapse, and to large, deep-seated landslides. The large landslides are often very slow moving but can accelerate during very wet periods. Soil erosion and landslides are also common on steep slopes in the Southern Alps foothills and the North Canterbury hill country, particularly the coastal hills around Kaikoura. Landslides and rock avalanches, particularly in steep valleys and gorges of the Southern Alps, can form dams which block rivers and create lakes. These dams can be dangerous because they can break suddenly, releasing a flood of water down the river. The likelihood of landslides is increased when people remove vegetation, excavate for buildings and roads, and change rainfall drainage.

 

Links:

 

NIWA; www.niwa.co.nz/natural-hazards/hazards/rainfall-triggered-landslides

Te Ara Encyclopedia of New Zealand www.teara.govt.nz/en/landslides

 

Tornado


Tornadoes are tightly spinning funnels of air extending down from thunderclouds, sometimes reaching the ground, with wind speeds up to 300 km/hr. Most tornados in New Zealand are small (10-20 metres wide on the ground) and last for less than 15 minutes, however they can cause a great deal of damage to buildings and infrastructure and harm to people and animals. They are most frequent in the west and north of New Zealand and are uncommon in Canterbury.

 

Links:

 

NIWA; www.niwa.co.nz/natural-hazards/hazards/extreme-weather-winds-and-tornadoesnbsp;

Te Ara Encyclopedia of New Zealand; www.teara.govt.nz/en/weather

 

Biological Hazards


Biological hazards include animal pests and diseases (such as varroa bee mite or foot-and-mouth disease), plant pests and diseases (such as didymo or PSA in kiwifruit), and aquatic (water) pests and diseases (such as sea squirt). These pests and diseases can reduce animal or plant productivity, increase pest control costs, or mean that the animal or plant cannot be eaten. In some cases, animal diseases such as avian influenza (bird flu) can be passed on to humans. Some diseases are have a relatively small impact and are able to be managed with little effort. However, other diseases such as foot-and-mouth disease are very contagious, can spread quickly and have no cure, meaning that if there were an outbreak quarantine measures would need to be put in place, having a large impact on transport and movement of animals or plants. Given the importance of agriculture in Canterbury, a disease outbreak would have a huge economic impact on the region.

 

Links:

 

Ministry for Primary Industries - Biosecurity; www.biosecurity.govt.nz

Te Ara Encyclopedia of New Zealand; www.teara.govt.nz/en/biosecurity

 

Climate change


Canterbury's climate varies from year to year but it is influenced by natural year- to decade-long climate cycles such as El Nino South Oscillation. Climate change is a longer-term change in climate caused by an increase of greenhouse gasses in the atmosphere, mostly carbon dioxide , methane and nitrous oxide from burning oil, gas and coal. The effects of climate change in Canterbury are likely to include more rain in the Southern Alps and less rain on the Canterbury Plains. Average temperature is likely to be 0.9 deg; warmer by 2040 compared to 1990, and 2 deg; warmer by 2090, with more hot days, fewer frosts and less snow. Climate change is also causing sea level to rise as ice caps melt we should be planning for a 0.8 metre increase by 2100 (from the 1980-1999 average). Climate change will probably increase the likelihood of flooding, severe weather, wild fire, landslides, and drought in some parts of Canterbury. Sea level rise will increase the likelihood of flooding in coastal areas and may cause or increase coastal erosion in some areas. Climate change may also change the types of animal and plant pests that we have in Canterbury as the average temperature increases.

 

Links:

 

ECan Climate Change information; http://ecan.govt.nz/advice/Sustainable-Living/Pages/climate-change.aspx

NIWA; http://www.niwa.co.nz/natural-hazards/hazards/climate-change

Ministry for the Environment; www.mfe.govt.nz/issues/climate/index.html

Te Ara Encyclopedia of New Zealand; www.teara.govt.nz/en/climate-change

 

Lifeline failure


Lifelines are infrastructure that provide vital services to the community, such as electricity, gas, petrol, water, wastewater, communications, roads, rail, ports, and airports. Canterbury, like the whole of New Zealand, is highly dependent on its infrastructure. Infrastructure networks are vulnerable to natural hazards, such as earthquakes, floods, tsunamis and landslides, but they can also be disrupted by other factors such as terrorism, or lack of maintenance or planning. Small lifeline infrastructure failures, such as short power cuts or a road affected by a small landslide, are relatively common and do not cause much disruption. However, widespread or long-term failure, such as power being cut for many days after a storm or earthquake, or a landslide blocking a main road for days, can cause distress or health issues for people and can affect the economy. The 2010/11 Canterbury earthquakes caused disruption to power, water, sewerage and transport networks for many months, and prolonged power cuts and road closures have occurred after snowstorms in 1992 and 2006.

 

Links:

 

Canterbury Lifelines Utilities Group; www.canterburylifelines.org.nz

Hazardous substances


Hazardous substances include fuel, flammable substances, explosives, toxic chemicals, pesticides, radioactive material, and waste contaminated by micro-organisms such as bacteria. Accidents involving a hazardous substances spill can be caused by natural hazards, such as an earthquake, tsunami, flood or landslide affecting a production or storage site, or a transport vehicle. Spills can also happen during transport accidents, or because of careless use, storage or disposal, or terrorism. Hazardous substance releases can cause death or injury to people and animals, and can harm the natural environment. Small hazardous substance spills are relatively common and can be dealt with by emergency services and local authorities. A large hazardous substance incident that would require a mass evacuation of people from an area is unlikely in Canterbury.

 

Links:

 

Environment Canterbury Hazardous Substance information http://ecan.govt.nz/advice/your-land/hazardous-substances/pages/default.aspx

Environmental Protection Agency; www.epa.govt.nz/hazardous-substances/Pages/default.aspx

Air accident


Canterbury has one international airport, at Christchurch, and smaller airports or aerodromes at Kaikoura, Hanmer Springs, Rangiora, West Melton, Ashburton, Timaru, Waimate, Tekapo, Pukaki and Mount Cook. An air accident can affect not only the aircraft but also people, buildings and infrastructure on the ground. The likelihood of a large air accident that emergency services cannot cope with is very small. Canterburys worst air accident occurred in June 2003 when a small charter aircraft crashed in fog near Christchurch airport, killing eight people.

 

Volcanic ash


There are no active volcanoes in the South Island. The volcanoes of Banks Peninsula have been extinct for around 5.8 million years, and there is no longer any molten rock (magma) under Banks Peninsula to create another eruption. However, volcanoes in the North Island could affect us here in Canterbury. Depending on which way the wind is blowing, a big eruption in the North Island could send volcanic ash our way, which can damage buildings, infrastructure and vegetation, and affect our health. We also need to be prepared for lots of people coming to the South Island if there is a big eruption in the North Island

 

Links:

 

GNS Science; www.gns.cri.nz/Home/Learning/Science-Topics/Volcanoes

GeoNet www.geonet.org.nz

Te Ara Encyclopedia of New Zealand http://www.teara.govt.nz/en/volcanoes

 

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