Auckland Region Emergency Management Group - CDEMG

The Auckland region is at risk from a number of natural and technological (man-made) hazards, for example, infrastructure (utility) failure, earthquakes, and volcanic eruptions. Many hazards have the potential to cause loss of life or injury. They could also damage homes and buildings, cause psychological stress, and result in significant economic loss.

Coastal Erosion & Flooding

The natural coastline processes of erosion and accretion can also be altered by human actions or human modification of the coastal environment. The amount and movement of sediment along the beach can be modified when humans place structures, extract sediment or undertake other works. This has been known to inhibit coastal accretion and enhance coastal erosion.

The coastal cliffs in Auckland are slowly eroding. Cliffs on Aucklands East Coast are most susceptible, eroding at a rate of approximately 2-6m per century. Erosion along West coast is 2 orders of magnitude smaller and is considered almost negligible, except near Awhitu.

Inundation (coastal flooding) of buildings, roads and properties is exacerbated when the beach is eroded as there is less protection offered by dunes and accreted beach sediment. Coastal flooding is commonly associated with severe storm events, and the occurrence of storm surge.

Biological hazards

There are a large range of biological hazards that if not controlled or avoided, could cause significant loss of life or severely affect New Zealand's economy, agricultural and fishery industries, health (human & animal), and infrastructure (e.g. water supply and treatment networks).

Due to our economic dependence on horticultural, agricultural and forestry industries, and limited historical exposure to disease, New Zealand is very susceptible to biological hazards.

For more information on biological hazards

Future changes in temperature, precipitation, and other climate variables will alter Auckland's soil moisture and mean sea level. Some locations will be more susceptible to floods and droughts.

What you can do to help reduce climate change

For more information on climate change

Five tropical cyclones have passed within 220km of Auckland City between 1970 and 2001. The main hazards associated with tropical cyclones are wind gusts and heavy rainfall, but they can also generate significant storm surge and coastal erosion.

For more information on Cyclones

Drought can be defined in various ways. An 'agricultural drought' is a period when the soil is estimated to be 'moisture deficit'. A significant agricultural drought can impact on Auckland's agricultural and horticultural industries. A 'hydrological drought' is when the effects of low precipitation affect hydrological systems. A hydrological drought can result in a water supply shortage, although storage capacity and demand are also important factors.

For more information on droughts

Although the Auckland region lies in one of the lowest earthquake activity regions of New Zealand, earthquakes of varying magnitude are likely to occur at some stage in the future.
Ground shaking that is severe enough to damage buildings built to earthquake code standards (~0.26 g) is expected to occur in Auckland, on average, once every two thousand years.

For more information on earthquakes

Every year Auckland has between 5000-6000 urban fires that require response from emergency services, and cause 10-15 fatalities. These a predominantly from house and industrial fires.

In the Auckland region there is a small risk of wildfire in the forested areas to the west (Waitakere Ranges), south (Hunua Ranges), northwest (Woodhill Forest), north (Mahurangi Forest) and east (Gulf Islands).

Fires in these areas can result from agricultural burn-off getting out of control, arson, careless actions (e.g. camp fires in restricted areas), or natural causes such as lightning strikes. Weather plays a significant factor - the risk of fire increases in prolonged drought conditions.

For more information on Fire

In the Auckland region, most flooding events are of short duration and affect relatively localised areas. Artificial drainage systems consisting of the primary piped system together with the overland flowpath are designed to cope with a 1:100 year a flood event (1 chance in 100 of occurring in any given year).

For more information on Flooding

Slope instability

The underlying causes of slope instability in the Auckland Region are fairly well known from case studies of specific failures. The causes can often be directly related to the rock and soil composition and the orientation of defects (e.g. bedding inclination, fractures, clay seams) with respect to slope. The degree of weathering and saturation are also significant factors. Some of these may be constant, or changed by new events (e.g. seismic activity or construction activity).

For more information on slope instability

Tornados frequently occur in Auckland but Aucklands tornados are much smaller than the very large ones that occur in the midwest of the United States.

Tornados are a mass of unstable air rotating up to 244 km/hr which rises rapidly around a centre of unstable air. On average, 1-2 tornadoes and watersprouts (tornadoes over water) are reported in Auckland every year. In New Zealand they usually have a damage path 10-20 m wide and 1-5 km long, and usually only have a life of around 15 minutes.

For more information on tornado

A tsunami is a series of waves that have long periods (usually 15-60 minutes), that are generated in a body of water by an impulsive disturbance that vertically displaces the water column. Tsunamis usually result from large-scale movement of the sea floor, from a volcanic eruption, submarine earthquake, or landslide.

For more information on tsunami

Volcanic Hazards

Much of Auckland is built on a potentially active volcanic field. Within an area of about 360 square kilometres, there are approximately 50 volcanoes. It is thought that Aucklands volcanoes first began to appear between 60 000 and 140 000 years ago, starting with the eruptions of Albert Park and the Domain. The largest and most recent eruption was Rangitoto, about 600 years ago, which would have been witnessed by local Maori.

None of these existing volcanoes are expected to erupt again. The next eruption will be in a new, unknown location. To gather information on the field, and help provide advance warning of any volcanic activity, the Auckland Regional Council monitors seismic activity in the Auckland area.

Auckland’s existing volcanoes are unlikely to become active again, since they all follow a pattern of short eruptions, but the Auckland Volcanic Field itself is young and still active, meaning new volcanoes could appear with little warning. In a city of a million people, even a small and brief eruption would be a major event.

For more information on volcanic hazards

Aircraft accidents

In NZ, over the last 2 years there have been 20-30 serious injuries or fatalities caused by Aircraft Accidents each year. Between 1996-1999 there were approximately 40 aircraft accidents in Auckland, approximately 13% of the total accidents recorded throughout New Zealand over this period. The majority of accidents occur upon small aircraft less than 2 721 kg of weight.

For more information on aircraft accidents

Computer Systems Failure

Computer systems network failure is primarily caused by power failure, but can also be caused by viruses, systems bugs e.g. Y2K, electromagnetic pulses, operating systems error, or by hackers.

Much of Aucklands infrastructure and most businesses are reliant on effective operation of computer networks, and this dependency is increasing through time. Systems failure occurs on a small scale quite frequently.
The likelihood of large scale systems failure that could significantly affect the region, like that that could have been caused by the Y2K bug is unknown. Heavily relied upon systems have complex back-up systems, but backup systems can fail.

For more information on computer systems failure

The Auckland region has a large number of dams for water supply, irrigation, farm waste treatment, stormwater treatment, sediment control, storing contaminated sediments and sewage treatment.
Approximately 50 dams in the Auckland region are large enough to cause significant damage if they failed. Dam failure can result from:

Most dam failures occur within the first few years of construction. In Auckland the majority of large dams in the region are more than 10 years old. Poor foundation materials, poor dam drainage, and weak construction materials are three primary factors associated with dam failure in New Zealand. The physical vulnerability of downstream features is determined prior to the dam construction.

For more information on dam failure

Hazardous Substances

Within the Auckland region, a variety of hazardous substances are transported, stored or utilised. Accidental release of these substances can cause harm to the health and safety of any person or the environment. Compared with other parts of New Zealand, e.g. Taranaki region, there are no significantly large hazardous substance production sites.

For more information on hazardous substances

Shipping Accident

Although there are no records of major shipping accidents within the Auckland harbours this is still a risk in this coastal region.
A worst case scenario would involve a major ship collision with a structure that carries are large number of people (e.g. Auckland Harbour Bridge).

For more information on shipping accident

The risk associated with large-scale vandalism or terrorism is variable, and depends upon what is targeted and how badly it is damaged. If terrorism in Auckland was targeted at significant infrastructure providers or heavily relied upon systems, terrorism could have significant consequences (refer to Infrastructure Failure and Computer Systems Failure).