Lake Taupo is the largest lake in New Zealand with an area of 616 km². With a length of 46km in length and 33km in width, the lake has a depth of 186m. The surroundings of the lake between 23 ° C and 11 ° C.
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For the time scale is here!
Formation of lake Taupo
The lake appeared 26,500 years ago following the explosion of a super volcano. It expelled more than 1000km² of ashes and molten rocks. The eruption is called Ourani with a degree of eruption of 8 on the volcanic explosivity index. The explosion is considered one of the most powerful since 70 000 years. The eruption produced a large amount of ash, igneous and magmatic rocks found throughout the North Island to a depth of 10m. It was so powerful that it devastated much of life on the North Island. Subsequently, more than 28 eruptions occurred over the last 26,500 years.
The ignimbre is a volcanic rock formed by debris of lava coming from a fiery cloud and welded. Before their cooling and they mixed with a vitreous matrix resulting from a rapid cooling of hot materials. The rock has a pumice look.
Pyroclastic flow
A f is a storm of hot gases with very high pressure which carries large quantities of lava debris (ashes and rocks). It covers hundreds of square kilometers of land in just a few hours. It can form during violent volcanic eruptions and travel at speeds over 100 km / h.
Here is a video showing the activity of a volcano producing a fiery cloud.
[kad_youtube url=”https://www.youtube.com/watch?v=rRKy3cehmnk” ]
In addition, the eruption allowed a large quantity of rhyolitic lava to be brought up.
Rhyolite lava
Rhyolitic lava is a viscous lava with a high (over-saturated) silica concentration. Rhyolite is a volcanic magmatic rock of fairly clear color: pink or gray and sometimes blue. The minerals visible to the naked eye within the rock are: quartz, feldspar and biotite.
Due to this vicious magma, the explosion resulted in the formation of a caldera. It was filled with water forming the Taupo Lake.
Formation caldera
The caldera is a collapse forming a crater. It is forming by an extreme and strong explosion of a volcanic eruption. The rhyolitic magma is vicious, which makes it sticky. This causes difficulties during the rise, causing an increase in the pressure in the magma chamber.
1) When the gas escapes, it will carry with it a large quantity of ash and magmatic debris in a strong volcanic explosion in the form of a fiery cloud.
2) The magma chamber is empty in its upper part.
3) It will undergo a collapse of the earth’s crust forming a crater called caldera.
4) Then fill up with water forming lakes for certain events.
Taupo Volcano
The Taupo volcano is considered the most active and largest producer of rhyolite magma in the world. Since the 26 500 years, there has been about one eruption every 900 years with the most recent 1800 years ago. One can be certain that it will again erupt! But we do not know two very important things. When will it erupt and what will be its intensity?
For all definitions: go to this page.
For the time scale is here!
Source
“The field guide to New Zealand Geology, An introduction to rocks, minerals and fossils”; Jocelyn Thrnton, Pinguin Books
“In search of ancient New-Zealand”; Hamish Campbell & Gerard Hutching; Pinguins books
