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Puhipuhi Embayment
The Puhipuhi Embayment (also Puhipuhi Basin) is a volcanic feature in Taupo Volcanic Zone of New Zealand associated with the collapse of the Ōkataina Caldera wall to its west. Its latest significant volcanic eruption was about 31,500 years ago and this dating required a reassessment of recent activity at the Eastern extension of the Tarawera vent alignment. Geography The Puhipuhi Embayment extends from the eastern margin of Mount Tarawera towards Kawerau including land mostly devoted to the Tarawera Forest portion of the Kaingaroa Forest. The basin is a dissected plateau at about above sea level. The Tarawera River cuts through the north of the basin and is its drainage. Geology Both the Pupipuhi Embayment and the Tarawera Volcanic Complex are part of the Ōkataina Volcanic Centre. There is a long eruptive history with the likelihood that some of the 13 Mangaone Subgroup eruptions were from vents in the embayment and the only dacite eruptives from this centre occur in the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
North Island
The North Island, also officially named Te Ika-a-Māui, is one of the two main islands of New Zealand, separated from the larger but much less populous South Island by the Cook Strait. The island's area is , making it the world's 14th-largest island. The world's 28th-most-populous island, Te Ika-a-Māui has a population of accounting for approximately % of the total residents of New Zealand. Twelve main urban areas (half of them officially cities) are in the North Island. From north to south, they are Whangārei, Auckland, Hamilton, Tauranga, Rotorua, Gisborne, New Plymouth, Napier, Hastings, Whanganui, Palmerston North, and New Zealand's capital city Wellington, which is located at the south-west tip of the island. Naming and usage Although the island has been known as the North Island for many years, in 2009 the New Zealand Geographic Board found that, along with the South Island, the North Island had no official name. After a public consultation, the board officially ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kaingaroa Forest
Kaingaroa Forest covers 2900 km² of the Bay of Plenty region of New Zealand, and is the largest forest plantation in New Zealand, and the second largest in the Southern Hemisphere (after the 6000km² Sabie/Graskop plantation in South Africa). The forest stretches from Lake Taupō in the south to Kawerau to the north. The headquarters of the forest are at the small settlement of Kaingaroa, Bay of Plenty, 50 kilometres southeast of Rotorua. Prior to planting the area was a tussock and scrub plateau (ranging between and high), formed on volcanic ash. The New Zealand Ministry for Culture and Heritage gives a translation of "long area of land" for ''Kāingaroa''. The forest was first planted in the late 1920s and owned as a state asset by the New Zealand government. Experimental planting of douglas fir and radiata pine began on a block at Kaingaroa in 1901 and continued from 1906 using Waiotapu prison labour. By 1932 the pines averaged high and in diameter. Later plan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calderas Of New Zealand
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 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 ', and Latin ', meaning "coo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Earthquake Swarm
In seismology, an earthquake swarm is a sequence of seismic events occurring in a local area within a relatively short period. The time span used to define a swarm varies, but may be days, months, or years. Such an energy release is different from the situation when a major earthquake (main shock) is followed by a series of aftershocks: in earthquake swarms, no single earthquake in the sequence is obviously the main shock. In particular, a cluster of aftershocks occurring after a mainshock ''is not'' a swarm. History and generalities In the Ore Mountains (Erzgebirge), which form the border between the Czech Republic and Germany, western Bohemia and the Vogtland region, have been known since the 16th century as prone to frequent earthquake swarms, which typically last a few weeks to a few months. Austrian geologist Josef Knett, while studying in 1899 a swarm of about a hundred events felt in western Bohemia/Vogtland in January-February 1824, coined the noun ''Schwarmbeben'', ' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dike (geology)
A dike or dyke, in Geology, geological usage, is a sheet of rock that is formed in a Fracture (geology), fracture of a pre-existing rock body. Dikes can be either Intrusive rock, magmatic or Sedimentary rock, sedimentary in origin. Magmatic dikes form when magma flows into a crack then solidifies as a sheet intrusion, either cutting across layers of rock or through a contiguous mass of rock. Clastic dikes are formed when sediment fills a pre-existing crack.Essentials of Geology, 3rd Ed, Stephen Marshak Magmatic dikes A magmatic dike is a sheet of igneous rock that cuts across older rock beds. It is formed when magma fills a fracture in the older beds and then cools and solidifies. The dike rock is usually more resistant to weathering than the surrounding rock, so that erosion exposes the dike as a natural wall or ridge. It is from these natural walls that dikes get their name. Dikes preserve a record of the fissures through which most mafic magma (fluid magma low in silica) reac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Basalt
Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial planet, rocky planet or natural satellite, moon. More than 90% of all volcanic rock on Earth is basalt. Rapid-cooling, fine-grained basalt is chemically equivalent to slow-cooling, coarse-grained gabbro. The eruption of basalt lava is observed by geologists at about 20 volcanoes per year. Basalt is also an important rock type on other planetary bodies in the Solar System. For example, the bulk of the plains of volcanism on Venus, Venus, which cover ~80% of the surface, are basaltic; the lunar mare, lunar maria are plains of flood-basaltic lava flows; and basalt is a common rock on the surface of Mars. Molten basalt lava has a low viscosity due to its relatively low silica content (between 45% and 52%), resulting in rapidly moving lava flo ... [...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] |
Rhyolite
Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained groundmass. The mineral assemblage is predominantly quartz, sanidine, and plagioclase. It is the extrusive equivalent to granite. Rhyolitic magma is extremely viscous, due to its high silica content. This favors explosive eruptions over effusive eruptions, so this type of magma is more often erupted as pyroclastic rock than as lava flows. Rhyolitic ash-flow tuffs are among the most voluminous of continental igneous rock formations. Rhyolitic tuff has been extensively used for construction. Obsidian, which is rhyolitic volcanic glass, has been used for tools from prehistoric times to the present day because it can be shaped to an extremely sharp edge. Rhyolitic pumice finds use as an abrasive, in concrete, and as a soil amendment. Description Rhyolite i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dacite
Dacite () is a volcanic rock formed by rapid solidification of lava that is high in silica and low in alkali metal oxides. It has a fine-grained (aphanitic) to porphyritic texture and is intermediate in composition between andesite and rhyolite. It is composed predominantly of plagioclase feldspar and quartz. Dacite is relatively common, occurring in many tectonic settings. It is associated with andesite and rhyolite as part of the subalkaline volcanic rock, subalkaline tholeiite, tholeiitic and calc-alkaline magma series. Composition Dacite consists mostly of plagioclase feldspar and quartz with biotite, hornblende, and pyroxene (augite or enstatite). The quartz appears as rounded, corroded phenocrysts, or as an element of the ground-mass. The plagioclase in dacite ranges from oligoclase to andesine and labradorite. Sanidine occurs, although in small proportions, in some dacites, and when abundant gives rise to rocks that form rhyodacite, transitions to the rhyolites. The rel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tarawera River
The Tarawera River is in the Bay of Plenty Region in the North Island of New Zealand. It flows from Lake Tarawera, northeastwards across the northern flanks of the active volcano Mount Tarawera, and past the town of Kawerau before turning north, reaching the Bay of Plenty west of Edgecumbe. The Tarawera Falls on the river are considered to be quite spectacular. Environmental issues The Tasman Pulp and Paper Mill, now owned by Norske Skog, has been discharging waste into the river since 1955. Local residents have erected signposts labelling the river as the "Black Drain" since the 1990s. The dark colour is due to the presence of pollution from farms, sewage and stormwater but it is predominantly from pulp and paper mill effluent. As of 1997, pulp and paper mills were discharging over 160 million litres of industrial waste into the river per day. By 2006, the oxygen levels in the river had reached a level where fish could survive, however the water colour was still dark. Since ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kawerau
Kawerau is a town in the Bay of Plenty region of the North Island of New Zealand. It is situated 100 km south-east of Tauranga and 58 km east of Rotorua. It is the seat of the Kawerau District Council, and the only town in Kawerau District. Kawerau is a small community, with an economy that is largely driven by the nearby pulp and paper mill that is run by Norske Skog and OJI Fibre Solutions. It is located along State Highway 34, southwest of Onepu, and is the terminus of the East Coast Main Trunk Railway, and the commencing point of the Murupara Branch railway. Kawerau was one of the worst-affected towns in the 1987 Edgecumbe earthquake. History and culture European settlement Kawerau, one of the youngest towns in New Zealand, was founded in 1953 as a mill town for the new Tasman pulp and paper mill. The site for the mill was chosen because of the ready availability of geothermal energy, water from the Tarawera River and the large supply of pine timber from the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
