Lauras New Zealand Volcano Report Document Transcript
New Zealand Volcanos What are Volcanos? Volcanos are found all over New Zealand. Volcanos are large hills or flat ground that are made when either two techtonic plates colide or if theres a weak spot or hot spot in the crust. New Zealand volcanos aremade by the both of these reasons, they have also formed lakes or basins such as Lake Taupo. How a Volcano Works? To form a Volcano a Subduction Zone happens. A Subduction Zone iswhen a techtonic plate colides with another or meets with another, which rattles the earth above. As the techtonic plates moves the ocean crustheats up forcing into the mantle. Then hot, boiling magma is produced, it is produced by high pressure and high heat rising higher, once the magma reaches the vent it turns to lava. The lava explodes and forms a volcano! New Zealand volcanos used this same process but in some cases such as Rangitoto, the techtonic plates didn’t move, instead there was a hot spot in the crust! What do Volcanos look like?Volcanoes shape and size depends on the explosion style, some may be lava flows and lava fields, some fire fountains and some explosive eruption. All of these explosion styles create a different shape and size.Lava flows and lava fields form a shield volcano which is a large long hill. It is usually formed by large lava flows! New Zealand VolcanosThere are over sixty volcanoes, basins and lakes in New Zealand. All thesevolcanos are different some big, some small, some coned shaped, someshields, there is even a lake. Auckland and Taupo have the largest volcanic fields in New Zealand, they are either active, dormant or extinct. When a Volcano is active it is still working, it means that there still could beanother eruption from an active volcano. A dormant volcano is a volcano that rarely erupts currently but may have erupted long ago in historic times. An extinct volcano is an volcano that scientists think that are unlikely to erupt again. Auckland Volcanic FieldAuckland volcanoes are different to other volcanos in New Zealand. They form not when techtonic plates colide but when there is a hotspot ormantle plumes in one of the techtonic plates, once the hotspot appears it
could take days for the volcano to actually rise and start the subduction zone process. Auckland volcanic field is made up of all Monogeneticvolcanoes, a Monogenetic volcano is a volcanic field of small, scatteredvents. The volcanoes have many monogenetic volcanoes inside the vent which erupts several times from that same vent over a long period of time. The small, scattered volcanoes are formed from magma bubbles,every magma bubble will produce another small volcano inside the vent. Thats why in Auckland there are so many volcanoes. Rangitoto Volcano Rangitoto Island is one of New Zealand’s largest volcanoes. The large eruption started with underwater eruptions building up, then a scoria cone formed by a fire fountain, later lava filled up and overflowed thecrater and lava spread on the sides creating a shield volcano. Rangitoto’s explosion was so large it erupted more volcanic material than all the other Auckland volcanoes put together, it erupted 2,300 million cubic meters of lava which would fill 468,000 Olympic sized swimming poolsand left 19 million cubic meters of tuff, ash and pyroclastics which would fill 3,800 Olympic sized swimming pools. Rangitoto Island has a distinct look, there is a scoria cone and two scoria mounds on the top of the volcano, also it looks like it has two peaks which it doesn’t. The scoriacone is so distinctive because the mounds on the scoria cones are from earlier eruptions and there is a deep crater in the scoria cone. The surface of Rangitoto is very rough, it is rough because the top layer of lava hardened but the lava underneath kept moving. Caves were made when the hot lava drained out which are still visible today. Rangitoto HistoryRangitoto is a big part of Maori history, a lot of people lived on Motutapu Island before and after the eruption occurred. The name Rangitoto wasshortened from Te Rangi-i-totonga-a-Tama-te-kapua which meant ‘Bloodof Tama-te-Kapua was shed’. He was a chief of Te Arawa canoe, he had to fight in hotorua, and he lost his life.Since the eruption Rangitoto and Motutapu Island have come together as one, it was used for burial, look out in case of war, fishing camps, parrot reserve and housing. On Rangitoto Island there are many baches asRangitoto came a public domain in 1890, people visited for day trips and picnics. Also money was raised by renting out places on camp sites, campers would build sheds to store there gear in. Overtime somechanges were made sheds were added to, sheds became holiday baches and now over 100 privately owned holiday baches are there. Even in the
1920s to 1930s prison labour was introduced to the Island, prisoners weforced to build roads, a swimming pool, a changing shed, a community hall, a tennis court and even a jetty. Plant Life There are a lot of different plants growing on Rangitoto now, there use to be no plants growing as it was hard to find soil and water beneath the hardened lava rocks. Many hundreds of years after the eruption, pohutukawa trees started growing beneath cracks in the lava rock, then other plants grew under the pohutukawa. The pohutukawa trees onRangitoto are over 200 years old, from then the volcano has grown many more plants. It has 228 species of native trees and flowering plants, 94 species of mosses, 67 species of liverworts, 54 kinds of fern and 21 species of orchid. On Rangitoto there are many unusual plants growingsuch as the pohutukawa and rata have bred together, epiphytes are found growing on the ground which usually grows on other plants, mangroves have been growing on lava, but they usually grow on salty mud flats and the alpine moss is growing by the sea it usually grows on top of mountains. Wild Life Rangitoto is full of wildlife, it is a home to many native and forest birds. Moreporks, Fantails, Grey Warblers, Silvereyes and are all forest birds, there are not many forest birds because in Rangitotos condition there isnt much food for the forest birds to eat. The Moreporks and Fantails are just some of the native birds living on the island, now that all pests have been removed from the island it makes it easier for them to survive. Thats why when you come to the island you have to check yourboats, shoes and bags for insects and pests to be most careful, also there is a strict no pets policy which is obeyed. Rangitoto community andconservations hope that Rangitoto will be become a wildlife sanctuary to protect the endangered and native wildlife that live on the island. Conclusion Rangitoto is a historic shield volcano that erupted over 600 years ago, it has two scoria cones and was formed by a hotspot in a techtonic plate. Over the years plants and trees have grown and the wildlife population has rose as it is going to try and become an animal sanctuary for endangered and native wildlife. Rangitoto is important to Auckland and always will be!