Geologic Issues: Landslides


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Overview and Current Tectonic Setting

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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...
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Resources: Minerals and the Ironsands

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...
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Geologic Issues: Volcanic Activity

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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...
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