22-590: The Raurimu Fault is the western Taupō rift -bounding north–south striking normal fault complex of the Ruapehu Graben , a seismically active area of the central North Island of New Zealand to the west of Mount Ruapehu . It is located near the western side of the Tongariro National Park , mainly in the Erua Forest, where it is along the western Waimarino Stream valley. The northern surface traces of
44-522: A recent shallow smaller earthquake swarm. Taup%C5%8D Rift The Taupō Rift is the seismically active rift valley containing the Taupō Volcanic Zone , central North Island of New Zealand . The Taupō Rift ( Taupo Rift ) is a 300 km (190 mi) intra-arc continental rift resulting from an oblique convergence in the Hikurangi subduction zone . The present young, modern Taupō Rift
66-584: A relatively short geological timeframe. In the Bay of Plenty region the current active faults of the old Taupō Rift can align with those of the modern Taupō Rift. This was illustrated by the Edgecumbe Fault and the off sea White Island Fault in the Whakatāne Graben of the rift. The parallel Tauranga Fault Zone to the north represents a now mainly inactive old Taupō Rift margin. Further south, where more of
88-602: 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 70 kilometres (43 mi) 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
110-593: Is driven by oral tradition reports of hundreds dying in a relatively recent landslip on the Waihi Fault Zone south of Lake Taupō it may not be true. Certainly in the context that the Taupō Volcano has been responsible for the largest eruption of the last 30,000 years being the Oruanui eruption , and the more recent smaller 232 ± 10 CE Hatepe eruption but both eruptions occurred before human settlement,
132-405: Is either graben or grabens . A graben is a valley with a distinct escarpment on each side caused by the displacement of a block of land downward. Graben often occur side by side with horsts . Horst and graben structures indicate tensional forces and crustal stretching. Graben are produced from parallel normal faults, where the displacement of the hanging wall is downward, while that of
154-610: Is preserved. The modern Taupō Volcanic Zone started forming 61,000 years ago but the modern Taupō Rift appears to only have intra-rift fault activity after the immensely disruptive Oruanui eruption . Earthquake activity in the Taupo Rift exhibits the entire spectrum of behaviour ranging from large, ground rupturing events to swarm activity comprising thousands of small events. In the time since Māori settlement these larger earthquakes can be speculated to have resulted in more indirect loss of life than volcanic activity, although as this
176-500: Is tectonic. The rift is in that part of the continental Australian Plate associated with the largely underwater Zealandia continental tectonic plate region. The rate of spread of the rift varies from effectively zero, at its southern inland end where the South Wanganui Basin is forming an initial back-arc basin, and volcanic activity has not yet begun, to in the Bay of Plenty as much as 19 mm (0.75 in)/yr. To
198-512: The Trans-Mexican Volcanic Belt result from a different tectonic process from the more studied intracontinental (intraplate) rifts it has been shown that the Taupō Rift displays all of the three modes of evolution. These are narrowing, lateral migration, and along-strike propagation, as found with intracontinental rifts. The Taupo Rift is widening much faster that other continental intraarc rifts, which might drive this evolution during
220-463: The footwall is upward. The faults typically dip toward the center of the graben from both sides. Horsts are parallel blocks that remain between graben; the bounding faults of a horst typically dip away from the center line of the horst. Single or multiple graben can produce a rift valley . In many rifts , the graben are asymmetric, with a major fault along only one of the boundaries, and these are known as half-graben. The polarity (throw direction) of
242-513: The fault alignment is crossed by the east west Ohakune Fault which creates just to the east of Ohakune a quite complex normal fault structure. The north south fault line resumes for a short distance from here until full transition near Raetihi into the east west alignment of the Taupō Rift termination faults beyond the Ruapehu Graben. The dip slip rate is 1.5 mm (0.059 in)/year with
SECTION 10
#1732869740274264-584: The fault commence near the Raurimu Spiral and the most southern surface is over 35 km (22 mi) to the south just to the east of the township of Raetihi . The northern end of the fault is intersected at the township of National Park by the National Park Fault which is the more northern Taupō Rift western wall fault. Lahar deposits of late Pleistocene (20,000 to 60,000 years ago) are offset by up to 60 m (200 ft). At its southern end
286-453: The last major displacement being 2.8 m (9 ft 2 in) at 2000 ± 300 years ago. It has a normal sense of throw, and a strike and dip of 005/53°E. A deep earthquake swarm not associated directly with the fault, but which was across it defines it as a shallow fault. The size of the characterised displacements indicates major earthquakes typical for the Taupō Rift are possible. The associated north eastern faults have been associated with
308-419: The main bounding faults typically alternates along the length of the rift. The asymmetry of a half-graben strongly affects syntectonic deposition. Comparatively little sediment enters the half-graben across the main bounding fault because of footwall uplift on the drainage systems. The exception is at any major offset in the bounding fault, where a relay ramp may provide an important sediment input point. Most of
330-436: The north but in the south increase to up to 10 kilometres (6.2 mi) separation. There are breaks in the intra-rift fault systems in the recently active central rhyolitic caldera segments at the Taupō Volcano and Ōkataina Caldera. In the later case, the strike of the basaltic dyke of the 1886 eruption of Mount Tarawera follows that of faults to the south and north, confirming other hints that orientation of volcanism
352-471: The north east it is related tectonically to the Havre Trough off the continental shelf which is also an active rift structure. The spread of the rift is associated with the basement graywacke rocks subsiding between the rift walls, so creating grabens infilled with volcanic deposits, sometimes from much higher volcanic mountains than the rift walls. Between 2016 and 2020 there was low volcanic activity in
374-519: The old Taupō Rift faults appear to be inactive, the active and very complex Taupō Fault Belt is orientated north-north-east. This is trending with the modern Taupō Rift alignment, which is not always quite parallel with the old rift alignment. Beyond Lake Taupō to the south, there is a relatively narrow rifting segment in the Tongariro graben which considerably widens at the Ruapehu graben. South of Ruapehu
396-434: The relative risk of earthquakes versus volcanoes depends upon time scale considered. Graben In geology , a graben ( / ˈ ɡ r ɑː b ən / ) is a depressed block of the crust of a planet or moon, bordered by parallel normal faults . Graben is a loan word from German , meaning 'ditch' or 'trench'. The first known usage of the word in the geologic context was by Eduard Suess in 1883. The plural form
418-565: The rift except at Whakaari / White Island , and the areas of maximal satellite measured subsidence were confined to a small areas of about 30 mm (1.2 in)/year near the 2012 Te Māri eruptions site, or the rift geothermal power stations, while from Lake Taupō to the coast subsidence more usually peaked at about 15 mm (0.59 in)/year. The majority of the fault activity is normal faulting . While continental intraarc rifts such as this, and those associated with Mount Aso in Japan, and
440-539: The rift, and its normal faulting, terminates with east to west faulting in the Taupō Rift termination faults . At the scale of the tectonic plate boundary, the rift trends NE-SW (41 ± 2°) but within New Zealand this trend is presently at 30° south of Lake Taupō and is 55° at the Bay of Plenty coast. A significant change in the mean fault strike occurs just south of the Ōkataina Caldera . The normal fault trends range from N20°E in
462-459: The south to N45°E in the central and northern sectors. There is good evidence that the orientation of intra-arc strike and extension processes has been maintained for 4 million years in this region of New Zealand. The modern active rift ranges in width from 15 kilometres (9.3 mi) in the northern Bay of Plenty sector, to 40 kilometres (25 mi) beyond Lake Taupō . Significant faults may be separated by as little as 100 metres (330 ft) in
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#1732869740274484-493: The volcanoes having potential for worldwide impact. The recent volcanism of the Taupō Volcanic Zone has been divided into three segments, with a central rhyolitic segment, dominated by explosive caldera associated with more typical Island Arc type andesite - dacite stratovolcanoes in either surrounding segment. In the hundreds of faults and their segments, some have associations with volcanism, but most fault activity
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