EOSC 311: Geoscape Project: Auckland, New Zealand

Auckland’s freshwater comes from dams, rivers and underground aquifers in the region. Contaminants such as debris and micro-organisms are present in this water, and thus needs to be filtered at treatment facilities prior to consumption. Auckland is beginning to have issues surrounding it’s freshwater – which has turned into a nationwide debate. As with any growing, metropolitan city, urban waterways are contaminated by the cities’ expansion. Rural land use practices, power generation and general pollution are driving factors in the issue. After a particularly bad storm in 2017 dubbed the ‘Tasmanian Tempest’, the Ardmore treatment plant stopped working for a short period and then functioned at low capacity when landslips and silt clogged the filters. The mass amounts of silt were due to deforestation in the Hunua Ranges – without forests to hold the earth together, soil washed into reservoirs. The water plant has since been upgraded so that it has a higher resilience to these...

Due to tectonic plate activity and subducting plates, volcanic activity is also common in the history and current state in New Zealand. There is a large volcanic zone, known as the Taupo Volcanic Zone on the North Island. As the Australian plate has stretched, it’s crust has become thinner than normal. Molten rock easily rises to the surface and through the thin crust and has erupted from volcanoes such as Ruapehu or Tongariro, or sits within the crust, heating it and water up, causing geothermal activity near Taupo and Rotorua. The city of Auckland sits on a volcanic field – known as the Auckland Volcanic Field with over 50 volcanos in an area of ~1000 square kilometers, which forms the hills, lakes and basins of the city. These volcanoes are fed by one magma source – a diffuse pool, occasionally finding its way to the surface, erupting in a different place each time. While the area is thought to be dormant as it is unlikely that the magma will push through the same place twic...

The Geologic history of New Zealand can be broken up into 6 stages: 3 sedimentation periods and 3 mountain building periods. 1. The early sedimentation depositional phase, Cambrian to Devonian period (about 545 to 370 million years) Earliest rock formations in new Zealand found today on South Island. At the time, New Zealand sat just off the ancient mega-continent of Gondwana. This included the formation of volcanic islands, which were eventually covered in sand and mud, subsequent land uplifting and erosion. 2. The Tuhua Orogeny, late Devonian to Carboniferous period (about 370 to 330 million years ago) Pressure and uplift characterized this period – which formed mountains with new minerals under great heat and pressure. These mountains were eventually eroded and covered by younger materials.   For example, sandstone and mudstone became schist, known for parallel layering of minerals like mica. Plutonic intrusions formed granite and diorite. 3. The New Zealand...

New Zealand is located at a subduction zone. Under the North Island (where Auckland is located), the Pacific plate is being subducted underneath the Australian plate. In contrast, the under the South Island, the Australian plate is being subducted under the Pacific plate. A major feature of the South Island is the Alpine fault, which forms the boundary between these two plates. This is a strike-slip fault (plates move side by side), and a large mountain region is located at the fault, uplifting slightly each year. With these tectonic features in mind, Auckland is susceptible to a variety of geological hazards, including but not limited to: slope instability, seismic, volcanic and tsunami hazards. The movement of these plates means that Auckland and New Zealand in general is greatly at risk of earthquakes.   In addition, there is also a long history of volcanic activity in this area due to subducting plates. In fact, Auckland sits on one of the most densely packed volca...

Torlesse supergroup Murihiku supergroup Alpine Fault Geothermal Energy Auckland Volcanic Field Taupo Volcanic Zone

New Zealand is a country rich in various natural resources, ranging from gold, silver, iron ore, coal, limestone to natural gas. Several other metallic minerals occur in New Zealand however are not currently produced, including copper, nickel, titanium and zinc. However, these would only be if it is economically feasible for the country. The area surrounding Auckland is specifically rich in clay, pumice, diatomite and coal, with nearby ironsands to the west – the country’s richest and largest reserves of ironsand. This black rocksand formed 2.5 million years ago from rock deposited on the coast by volcanic activity in the Taranaki region. Over time, this heavy, dark ironsand was transported by ocean currents along the west coast of the North Island and deposited on beaches. Ironsand contains the following minerals (??): magnetite, titanium oxide and vanadium oxide. These components can be used in the production of steel, producing titanium which is then used in high-tech...

New Zealand sources as much of its energy as possible from natural resources. In 2017, 82% was from renewable resources – including sunlight, wind, water and geothermal heat sources. Hydro and geothermal energy are continually the largest contributors to New Zealand’s energy supply. Geothermal continues to be the most inexpensive source of new energy and one of the most reliable due to its lack of dependence on the weather. The Taupo Volcanic Zone on the North Island has some of the country’s highest-temperature geothermal fields which also boasts the majority of the generation facilities. There are other plants at other faults and tectonic features across the country. While geothermal energy is renewable and abundant in New Zealand, it requires careful management and monitoring to control water and pressure levels and prevent land subsidence and depletion. Geothermal fluids also contain gases and minerals, and the amount released depends on the design of the plant, meaning t...

The earthquakes in New Zealand occur due to the collision between the Australian and Pacific plates. The boundary between these two plates runs diagonally across the country, and the pattern of earthquakes reflects the activity of the plates along their boundaries. For example, oceanic crust of the Pacific plate is subducting under the eastern North Island and Marlborough and these are distinct areas of deep earthquakes. Subduction causes deep earthquakes within the sinking crust as the slabs are bent downwards. The land here has faulted, with blocks shifting horizontally and vertically, forming the Tararua Mountain Range. Movement along these faults cause deep earthquakes – several magnitude 7 or greater. Generally, shallow earthquakes occur to the southeast of this seismic zone, with deeper ones towards the northeast. This pattern reflects the northwest dip/slope of the boundary between the two plates (the Benioff zone). Other types of earthquakes are common in New Zealand...