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North Island Volcanic Plateau
The North Island Volcanic Plateau (often called the Central Plateau and occasionally the Waimarino Plateau) is a volcanic plateau covering much of central North Island of New Zealand with volcanoes, lava plateaus, and crater lakes. It contains the Taupō caldera complex, Okataina caldera complex and Tongariro Volcanic Centre being currently the most frequently active and productive area of silicic volcanism on Earth. New Zealand is part of the Pacific Ring of Fire. Location and description The plateau is approximately east–west and the north–south distance is about . Extensive ignimbrite sheets spread east and west from the Central Taupō Volcanic Zone, centred on the huge active supervolcanic caldera of Lake Taupō, now the largest lake in New Zealand. This last erupted less than 2000 years ago. The volcanic area includes the three active peaks of Mount Tongariro, Mount Ngāuruhoe, and Mount Ruapehu in the south, and extends beyond Rotorua in the north reaching ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcanic Plateau
A volcanic plateau is a plateau produced by volcanic activity. There are two main types: lava plateaus and pyroclastic plateaus. Lava plateau Lava plateaus are formed by highly fluid basaltic lava during numerous successive eruptions through numerous vents without violent explosions (quiet eruptions). These eruptions are quiet because of low viscosity of lava, so that it is very fluid and contains a small amount of trapped gases. The resulting sheet lava flows may be extruded from linear fissures or rifts or gigantic volcanic eruptions through multiple vents characteristic of the prehistoric era which produced giant flood basalts. Multiple successive and extensive lava flows cover the original landscape to eventually form a plateau, which may contain lava fields, cinder cones, shield volcanoes and other volcanic landforms. In some cases, a lava plateau may be part of a single volcano. An example is the massive Level Mountain shield volcano in northern British Columbia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kaituna River
The Kaituna River is in the Bay of Plenty region of the North Island of New Zealand. It is the outflow from Lakes Lake Rotorua, Rotorua and Lake Rotoiti (Bay of Plenty), Rotoiti, and flows northwards for , emptying into the Bay of Plenty near Te Puke. It was the subject of a claim concerning the effluent flowing down the river from Lake Rotorua, which resulted in movement to a land treatment system. The New Zealand Ministry for Culture and Heritage gives a translation of "eat eels" for ''Kaituna''. The upper section of the Kaituna, also referred to as Okere River, offers some of the best whitewater kayaking and rafting in the world, with the Okere Falls area containing the highest commercially rafted waterfall, , in the world. It is also famous for its trout fishing. Cultural claim During the 1970s Lake Rotorua was becoming eutrophication, eutrophic under heavy nutrient loadings, leading the New Zealand Ministry of Works, Ministry of Works to propose diverting some sewage flow ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mount Ngauruhoe
Mount Ngāuruhoe (also spelled Ngauruhoe; Māori: ''Ngāuruhoe'') is a volcanic cone in New Zealand. It is the youngest vent in the Tongariro stratovolcano complex on the Central Plateau of the North Island and first erupted about 2,500 years ago. Although often regarded as a separate mountain, geologically, it is a secondary cone of Mount Tongariro. The volcano lies between the active volcanoes of Mount Tongariro to the north and Mount Ruapehu to the south, to the west of the Rangipo Desert and 25 kilometres to the south of the southern shore of Lake Taupō. Etymology The local Māori traditions state that the volcano was named by Ngātoro-i-rangi, an ancestor of the local Māori iwi, Ngāti Tūwharetoa. Ngātoro-i-rangi called volcanic fire from his homeland Hawaiki, which eventually emerged at Ngāuruhoe. The name given by Ngātoro-i-rangi (Ngāuruhoe) either commemorates his slave, who had died from the cold before the fire arrived, or refers to the insertions ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mount Tongariro
Mount Tongariro (; ) is a compound volcano in the Taupō Volcanic Zone of the North Island of New Zealand. It is located to the southwest of Lake Taupō, and is the northernmost of the three active volcanoes that dominate the landscape of the central North Island. Geology Mount Tongariro is part of the Tongariro volcanic centre, which consists of four massifs made of andesite: Tongariro, Kakaramea-Tihia Massif, Pihanga, and Ruapehu at the southern end of the North Island Volcanic Plateau. The andesitic eruptions formed Tongariro, a steep stratovolcano, reaching a height of . Tongariro is composed of layers of both lava and tephra and the eruptions that built the current stratovolcano commenced about 275,000 years ago. Tongariro consists of at least 12 cones. Ngāuruhoe, while often regarded as a separate mountain, is geologically a cone of Tongariro. It is also the most active vent, having erupted more than 70 times since 1839, the last episode in 1973 to 1975. Activity h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caldera
A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is gone. The ground surface then collapses into the emptied or partially emptied magma chamber, leaving a large depression at the surface (from one to dozens of kilometers in diameter). Although sometimes described as a Volcanic crater, crater, the feature is actually a type of sinkhole, as it is formed through subsidence and collapse rather than an explosion or impact. Compared to the thousands of volcanic eruptions that occur each century, the formation of a caldera is a rare event, occurring only a few times per century. Only seven caldera-forming collapses are known to have occurred between 1911 and 2016. More recently, a caldera collapse occurred at Kīlauea, Hawaii in 2018. Etymology The term ''caldera'' comes from Spanish language, S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supervolcano
A supervolcano is a volcano that has had an eruption with a Volcanic Explosivity Index (VEI) of 8, the largest recorded value on the index. This means the volume of deposits for such an eruption is greater than 1,000 cubic kilometers (240 cubic miles). Supervolcanoes occur when magma in the mantle rises into the crust but is unable to break through it. Pressure builds in a large and growing magma pool until the crust is unable to contain the pressure and ruptures. This can occur at hotspots (for example, Yellowstone Caldera) or at subduction zones (for example, Toba). Large-volume supervolcanic eruptions are also often associated with large igneous provinces, which can cover huge areas with lava and volcanic ash. These can cause long-lasting climate change (such as the triggering of a small ice age) and threaten species with extinction. The Oruanui eruption of New Zealand's Taupō Volcano (about 26,500 years ago) was the world's most recent VEI-8 eruption. Terminology ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ignimbrite
Ignimbrite is a type of volcanic rock, consisting of hardened tuff. Ignimbrites form from the deposits of pyroclastic flows, which are a hot suspension of particles and gases flowing rapidly from a volcano, driven by being denser than the surrounding atmosphere. New Zealand geologist Patrick Marshall (1869-1950) coined the term ''ignimbrite'' from the Latin ''igni-'' [fire] and ''imbri-'' [rain]. Ignimbrites are made of a very poorly sorted mixture of volcanic ash (or tuff when Lithification, lithified) and pumice lapilli, commonly with scattered lithic fragments. The ash is composed of glass shards and crystal fragments. Ignimbrites may be loose and unconsolidated, or lithified (solidified) rock called lapilli-tuff. Near the volcanic source, ignimbrites often contain thick accumulations of lithic blocks, and distally, many show meter-thick accumulations of rounded cobbles of pumice. Ignimbrites may be white, grey, pink, beige, brown, or black depending on their composition and d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pacific Ring Of Fire
The Ring of Fire (also known as the Pacific Ring of Fire, the Rim of Fire, the Girdle of Fire or the Circum-Pacific belt) is a region around much of the rim of the Pacific Ocean where many Types of volcanic eruptions, volcanic eruptions and earthquakes occur. The Ring of Fire is a Horseshoe, horseshoe-shaped belt about long and up to about wide. The Ring of Fire includes the Pacific coasts of South America, North America and Kamchatka, and some islands in the western Pacific Ocean. Although there is consensus among geologists about almost all areas which are included in the Ring of Fire, they disagree about the inclusion or exclusion of a few areas, for example, the Antarctic Peninsula and western Indonesia. The Ring of Fire is a direct result of plate tectonics: specifically the movement, collision and destruction of lithosphere, lithospheric plates (e.g. the Pacific Plate) under and around the Pacific Ocean. The collisions have created a nearly continuous series of subdu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcanism
Volcanism, vulcanism or volcanicity is the phenomenon of eruption of molten rock (magma) onto the surface of the Earth or a solid-surface planet or moon, where lava, pyroclastics, and volcanic gases erupt through a break in the surface called a vent. It includes all phenomena resulting from and causing magma within the crust or mantle of the body, to rise through the crust and form volcanic rocks on the surface. Magmas, that reach the surface and solidify, form extrusive landforms. Volcanic processes Magma from the mantle or lower crust rises through the crust towards the surface. If magma reaches the surface, its behavior depends on the viscosity of the molten constituent rock. Viscous (thick) magma produces volcanoes characterised by explosive eruptions, while non-viscous (runny) magma produce volcanoes characterised by effusive eruptions pouring large amounts of lava onto the surface. In some cases, rising magma can cool and solidify without reaching the surface. Inste ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silicic
Silicic is an adjective to describe magma or igneous rock rich in silica. The amount of silica that constitutes a silicic rock is usually defined as at least 63 percent. Granite and rhyolite are the most common silicic rocks. Silicic is the group of silicate magmas which will eventually crystallise a relatively small proportion of ferromagnesian silicates, such as amphibole, pyroxene, and biotite. The main constituents of a silicic rock will be minerals rich in silica-minerals, like silicic Feldspar or even free silica as Quartz. Example The " Shammar group" is a silicic and volcaniclastic sequence in northwestern Saudi Arabia. See also *Felsic *Mafic A mafic mineral or rock is a silicate mineral or igneous rock rich in magnesium and iron. Most mafic minerals are dark in color, and common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite. Common mafic rocks include ... References Igneous rocks {{Petrology-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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