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Horohoro Fault
The Horohoro Fault is in the old Taupō Rift of the central North Island of New Zealand and is associated with the spectacular Horohoro cliffs. Geology Just south of Lake Rotorua, Horohoro mountain, a rhyolite dome, has very high cliffs in an apparent fault scarp that defines the western edge of the lower lying Paeroa Garben and its northern Kapenga Caldera. The Paeroa Garben's eastern edge is defined by the Paeroa Fault. The cliffs are composed of Mamaku ignimbrite from the Rotorua Caldera eruption and older ignimbrites and Rotorua rhyolite. This fault area of the Taupō Rift is controversial as the components of historic tectonic and volcanic contribution have led to debate. Some authors have also extended and widened the definition of the Ngakuru Graben, which is to the south, during this debate. The northern portion of the fault for the last 20,000 years is displacing at a low rate of up to 0.2 mm/yr but it is unknown if the southern portion is active. The far north ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Horohoro, New Zealand
Horohoro is a rural farming community 15 kilometers (9.3 mi) southwest of Rotorua, New Zealand. Horohoro is a flat-topped mountain with perpendicular cliffs and is a prominent landmark in the Rotorua area. It is the traditional home of the Ngāti Kea Ngāti Tuarā people. The Ngāti Kea Ngāti Tuarā ancestral story tells of an incident in which Kahumatamomoe, a Te Arawa chief, washed his hands in a stream at the northern end of the Horohoro mountain. Following this story, the full name of the mountain is Te Horohoroinga-o-ngā-ringa-o-Kahumatamomoe (''Washing of Kahumatamomoe's hands''). The 1929 land development project by Āpirana Ngata proposed the building of farms on Māori land. Horohoro was among the first areas addressed by the plan and migrants came to work on the project. Horohoro has two maraes belonging to Ngāti Kea Ngāti Tuarā: Kearoa marae and Rongomaipapa marae. Rongomaipapa marae is also affiliated with Tūhourangi and Ngāti Kahungunu Ngāti Kahun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Normal Fault
In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic forces, with the largest forming the boundaries between the plates, such as the megathrust faults of subduction zones or transform faults. Energy release associated with rapid movement on active faults is the cause of most earthquakes. Faults may also displace slowly, by aseismic creep. A ''fault plane'' is the plane that represents the fracture surface of a fault. A ''fault trace'' or ''fault line'' is a place where the fault can be seen or mapped on the surface. A fault trace is also the line commonly plotted on geologic maps to represent a fault. A ''fault zone'' is a cluster of parallel faults. However, the term is also used for the zone of crushed rock along a single fault. Prolonged motion along closely spaced faults can blur the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hatepe Eruption
The Hatepe eruption, named for the Hatepe Plinian pumice tephra layer, sometimes referred to as the Taupō eruption or Horomatangi Reef Unit Y eruption, is dated to 232 CE ± 10 and was Taupō Volcano's most recent major eruption. It is thought to be New Zealand's largest eruption within the last 20,000 years. The eruption ejected some of material, of which just over was ejected in a few minutes. This makes it one of the largest eruptions in the last 5,000 years, comparable to the Minoan eruption in the 2nd millennium BCE, the 946 eruption of Paektu Mountain, the 1257 eruption of Mount Samalas, and the 1815 eruption of Mount Tambora. Stages of the eruption The eruption went through several stages, with six distinct marker horizons identified. Despite the uniform composition of the erupted magma, a wide variety of eruptive styles were displayed, including weak phreatomagmatism, Plinian eruptions, and a huge pyroclastic flow. Rhyolitic lava domes were extruded some ye ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ngakuru Graben
The Ngakuru Graben is an area of tectonic ground subsiding as originally defined between the Ngakuru Fault to the east and the Whirinaki Fault in the west both in the Taupō Fault Belt. It was originally defined in 1959Grindley, G. W., 1959, Geological Map NZ 1:63360,Sheet 8, Waiotapu. DSIR. but many other geological terms for local features are no longer in use, and some were misinterpretations. Within this wide Ngakuru Graben are also to the west the Maleme Fault (Zone), which as a zone also contains the Mangaete/Lakeside Fault and to the east the Hossack Road Fault and the Te Weta Fault. Some authors have defined a wider wide area so as to include all of the low-lying areas associated with the Taupō Fault Belt The Taupō Fault Belt contains many almost parallel active faults, and is located in the Taupō Rift of the central North Island of New Zealand geographically between Lake Taupō and the lakes of Rotorua, Tarawera, Rotomahana and Rerewhakaaitu. ... immediately sout ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rotorua Caldera
The Rotorua Caldera, now in filled with Lake Rotorua, is a large rhyolitic caldera. It is one of several large volcanoes located in the Taupō Volcanic Zone on the North Island of New Zealand. Geography The major regional settlement of Rotorua is located in the caldera. There is geothermal activity in the city of Rotorua and the geothermal areas of Tikitere and Whakarewarewa are associated with the caldera. These areas are still associated with small hydrothermal eruptions. Geology Eruption history The caldera was formed in a single event paired List of large volcanic eruptions, major eruption, that lasted only weeks, is now dated about 240,000 years ago, and which ejected more than of rhyolitic Mamaku ignimbrite giving it a Volcanic Explosivity Index of 7. The eruption has been reinterpreted as a paired eruption with a very slightly later, slightly smaller southerly eruption from the same mush body feeding the Ohakuri Caldera. Ignimbrite, up to thick covering about , was depo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paeroa Fault
The Paeroa Fault is a seismically active area in the Taupō District, Waikato, Waikato Region of the central North Island of New Zealand. Geology North of Lake Taupō, volcanic ignimbrite at least thick, and called the Paeroa Ignimbrite (dated to 339 ± 5 ) is exposed along the very steep fault scarp of the Paeroa Fault that defines the western flank of the high Paeroa Range. The Paeroa Ignimbrite appears to have been erupted from a linear vent alignment parallel to the current Paeroa Range and fault. This fault area of the Taupo Rift is displacing at a rate of /year. At the north eastern end of the fault is the geothermally active Maungaongaonga volcano that with the fault defines the far south western border of the :Okataina Volcanic Centre, Ōkataina Volcanic Centre. The Ngapouri-Rotomahana Fault too extends to the Ōkataina Caldera and is a splay from the Paeroa Fault. The southern portion of the fault is associated with the raised Paeroa Fault block immediately to its e ... [...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] |
Taupō Rift
The Taupō Rift is the seismically active rift valley containing the Taupō Volcanic Zone, central North Island of New Zealand. Geology The Taupō Rift (Taupo Rift) is a intra-arc continental rift resulting from an oblique convergence in the Hikurangi subduction zone. The present young, modern Taupō Rift is defined by events between 25,000 and 350,000 years and the old Taupō Rift system which can be defined by a gravity anomaly is now located more to the north being created between 350,000 and 2 million years and is about wide. Consensus does not yet exist with regard to the cause of the Taupō Rift's extension or the exceptional volcanic productivity of the associated Taupō Volcanic Zone. Its geology and landforms are of worldwide interest and it contains multiple significant faults and volcanoes with some of the volcanoes having potential for worldwide impact. Volcanic context The recent volcanism of the Taupō Volcanic Zone has been divided into three segments with a cent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Taupō Volcanic Zone
The Taupō Volcanic Zone (TVZ) is a volcanic area in the North Island of New Zealand that has been active for the past two million years and is still highly active. Mount Ruapehu marks its south-western end and the zone runs north-eastward through the Taupō and Rotorua areas and offshore into the Bay of Plenty. It is part of the larger Central Volcanic Region that extends further westward through the western Bay of Plenty to the eastern side of the Coromandel Peninsula and has been active for four million years. At Taupō the rift volcanic zone is widening east–west at the rate of about 8 mm per year while at Mount Ruapehu it is only 2–4 mm per year but this increases at the north eastern end at the Bay of Plenty coast to 10–15 mm per year. It is named after Lake Taupō, the flooded caldera of the largest volcano in the zone, the Taupō Volcano and contains a large central volcanic plateau as well as other landforms associated with its containing tectonic i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Holocene
The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene together form the Quaternary period. The Holocene has been identified with the current warm period, known as MIS 1. It is considered by some to be an interglacial period within the Pleistocene Epoch, called the Flandrian interglacial.Oxford University Press – Why Geography Matters: More Than Ever (book) – "Holocene Humanity" section https://books.google.com/books?id=7P0_sWIcBNsC The Holocene corresponds with the rapid proliferation, growth and impacts of the human species worldwide, including all of its written history, technological revolutions, development of major civilizations, and overall significant transition towards urban living in the present. The human impact on modern-era Earth and its ecosystems may be considered of global si ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Miocene
The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recent" because it has 18% fewer modern marine invertebrates than the Pliocene has. The Miocene is preceded by the Oligocene and is followed by the Pliocene. As Earth went from the Oligocene through the Miocene and into the Pliocene, the climate slowly cooled towards a series of ice ages. The Miocene boundaries are not marked by a single distinct global event but consist rather of regionally defined boundaries between the warmer Oligocene and the cooler Pliocene Epoch. During the Early Miocene, the Arabian Peninsula collided with Eurasia, severing the connection between the Mediterranean and Indian Ocean, and allowing a faunal interchange to occur between Eurasia and Africa, including the dispersal of proboscideans into Eurasia. During the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Active Fault
An active fault is a fault that is likely to become the source of another earthquake sometime in the future. Geologists commonly consider faults to be active if there has been movement observed or evidence of seismic activity during the last 10,000 years. * Active faulting is considered to be a geologic hazard - one related to earthquakes as a cause. Effects of movement on an active fault include strong ground motion, surface faulting, tectonic deformation, landslides and rockfalls, liquefaction, tsunamis, and seiches. Quaternary faults are those active faults that have been recognized at the surface and which have evidence of movement during the Quaternary Period. Related geological disciplines for ''active-fault'' studies include geomorphology, seismology, reflection seismology, plate tectonics, geodetics and remote sensing, risk analysis, and others. Location Active faults tend to occur in the vicinity of tectonic plate boundaries, and active fault research has foc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
