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Topic: Tonga Trench


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In the News (Fri 19 Apr 19)

  
  Oceanic trench - Wikipedia, the free encyclopedia
Trenches along with volcanic arcs and zones of earthquakes that dip under the volcanic arc as deeply as 700 km are diagnostic of convergent plate boundaries and their deeper manifestations, subduction zones.
Trenches are centerpieces of the distinctive physiography of a convergent plate margin.
Trenches distant from an influx of continental sediments lack an accretionary prism, and the inner slope of such trenches is commonly composed of igneous or metamorphic rocks.
en.wikipedia.org /wiki/Oceanic_trench   (3704 words)

  
 Bathymetry of the Tonga Trench and Forearc: A Map Series
Tonga is recognized as the type example of an extension-dominated, non-accretionary convergent margin (e.g., Tappin, 1994; Tappin et al., 1994a; MacLeod, 1996), with active extensional tectonism throughout the forearc and landward trench slopes.
The axis of the Tonga Trench is offset roughly 50 km to the northwest, relative to the axis of the Kermadec Trench (Figure 1).
The Tonga Trench and forearc are dominated by abundant normal faulting, and typically have numerous canyons that allow substantial volumes of material to move from the Tonga platform to middle and lower slope basins.
dusk2.geo.orst.edu /tonga   (9452 words)

  
 ninemsn Encarta - Search Results - Tonga
Tonga, independent Polynesian monarchy in the south-western Pacific Ocean, situated about 650 km (400 mi) east of Fiji and 2,003 km (1,245 mi)...
Tonga Trench, world’s second deepest point after the Mariana Trench.
Located in the South Pacific Ocean, the trench is an active subduction boundary....
au.encarta.msn.com /Tonga.html   (85 words)

  
 The Philippine Trench   (Site not responding. Last check: 2007-10-20)
Until 1970 the Philippine Trench was regarded as the deepest point of the earth.
Deeper is the Mariana Trench (11,034 meters), the Tonga Trench (10,882 meters) and the Kuril Trench (10,542 meters).
In the Philippine Trench in a depth of until up to three miles one of the world-largest deposits of deuterium (heavier hydrogen) was also found.
home.arcor.de /be/bethge/philippinetrench.htm   (616 words)

  
 Tonga Experience (Tonga Visitor Information)   (Site not responding. Last check: 2007-10-20)
Tonga consists of 176 islands ranging from high volcanic to low coral terrain create scenic variety seldom matched elsewhere in the world.
In all, Tonga is comprised of 176 coral and volcanic islands, thirty-six of which are inhabited.
Tonga is located on the eastern edge of the Indo-Australian Plate, which is forced up by the Pacific Plate pushing under it at the Tonga Trench.
www.tongaexperience.com /pages/info.html   (979 words)

  
 Inverted Mountains
Trenches mostly lie parallel or adjacent to island arcs or mountain ranges of the continental margins.
The trench margins are destructive because this is the region where the oceanic rocks are carried down after colliding with a continental plate.
Trenches form and last long because the rate of the plates moving away or towards each other is just 1-2 inches per year.
www.upd.edu.ph /~ismed/agham/archive/3rd/extras/nikki/trenches.htm   (1066 words)

  
 Ufficio del Turismo di Tonga in Italia - News
The proposed investigation will focus on the biology of the Tonga Trench, and among the proposed activities will be to collect a variety of samples from depths of 2,000 meters down to the maximum depth of approximately 10,800 meters.
First, the Tonga Trench is the coldest known habitat with a depth of 10,800 meters.
Judging from appropriate sources made in the 1950s, the researchers predict that the temperature in the Tonga Trench at its greatest depths will be close to 2° C. This contrasts with the temperature in the Mariana Trench of approximately 2.5° C at comparable depth.
www.tongaturismo.info /news.htm   (1727 words)

  
 Pacific Ring of Fire - Wikipedia, the free encyclopedia
It is associated with a nearly continuous series of oceanic trenches, island arcs, and volcanic mountain ranges and / or plate movements.
The southern portion is more complex with a number of smaller tectonic plates in collision with the Pacific plate from the Mariana Islands, the Philippines, Bougainville, Tonga, and New Zealand.
Indonesia lies between the Ring of Fire along the northeastern islands adjacent to and including New Guinea and the Alpide belt along the south and west from Sumatra, Java, Bali, Flores, and Timor.
en.wikipedia.org /wiki/Pacific_Ring_of_Fire   (387 words)

  
 Tonga Trench   (Site not responding. Last check: 2007-10-20)
The Tonga Trench and its forearc form an active convergent margin between two plates of the lithosphere, the Pacific plate being subducted into the earth'ssemi-molten aesthenosphere,and the northeastern corner of the Australian plate overriding it.
The Tonga trench extends north-northeast from the North Island of NewZealand.
Along the Tonga Trench mantle-derived melts are transferred to the island arc systems, and abyssaloceanic sediments and fragments of oceanic crust are collected.
www.therfcc.org /tonga-trench-14945.html   (185 words)

  
 Cruise Plan
First, the Tonga Trench is the coldest known habitat having a depth of 10,800 meters.
Judging from determinations made in the 1950s, we expect that the temperature in the Tonga Trench at its greatest depths will be close to 2°C. This contrasts to the temperature in the Mariana Trench of approximately 2.5°C at a comparable depth.
The Tonga Trench is one of the most seismically active trenches in the world.
sio.ucsd.edu /supp_groups/shipsked/2000/allships2000/2000MV/Yayanos/YayanosPlan.html   (734 words)

  
 CVO Website - Tonga Volcanoes and Volcanics
The unbroken line of subduction, from New Zealand through the Kermadecs and Tonga, ends abruptly and the trench swings west toward the remarkable, donut-shaped island of Niuafo'ou, a basaltic shield volcano with a large, lake-filled caldera.
The Tonga Archipelago stretches 250 kilometers along the western margin of the Tonga Trench in the southern Pacific Ocean.
The Kingdom of Tonga is an archipelago of two parallel island belts: that to the east is low, fertile, coralline, and well populated, while that to the west is young, volcanic, and ranges from steep cones to ephemeral islands.
vulcan.wr.usgs.gov /Volcanoes/Tonga/description_tonga_volcanoes.html   (1255 words)

  
 release 1982 1006
In addition, the trenches along the west and northwest margins of the Pacific plate are clearly visible.
swell occurs seaward of the trench, as the oceanic crust buckles upward prior to subduction.
Its depth and "nested" shape relative to the present trench to the northeast suggest that it is fossil (ancient) trench, which may mark former position of the New Hebrides subduction zone.
www.jpl.nasa.gov /releases/80s/release_1982_1006.html   (1208 words)

  
 History. (from Tonga) --  Encyclopædia Britannica   (Site not responding. Last check: 2007-10-20)
Tonga was inhabited at least 3,000 years ago by Austronesian-speaking peoples who made elaborately decorated Lapita pottery similar to that found on Fiji.
Tonga's total land area of 290 square miles (750 square kilometres) is dispersed between...
Tonga's closest neighbors are Fiji, Samoa, and Niue.
www.britannica.com /eb/article-7337?tocId=7337   (883 words)

  
 MRD Info. Note 10 Plate Tectonic History of Fiji   (Site not responding. Last check: 2007-10-20)
As a result of the seafloor spreading in the Lau Basin, the Lau Arc became isolated from effects of subduction at the Tonga Trench portion of the old Vityaz Trench.
This is related to westward subduction of the Pacific Plate under the Indo-Australian Plate at the Tonga Trench.
Present-day volcanism occurs in the Tonga and New Hebrides Arcs.
www.mrd.gov.fj /gfiji/geology/educate/platect.html   (2043 words)

  
 Journal Contents - Analogue modelling of asymmetrical back-arc extension   (Site not responding. Last check: 2007-10-20)
The first example is the Tonga Arc from the southwest Pacific and the second example is the Ryukyu Arc from the Philippine Sea.
The Tonga arc is the northernmost half of the Tonga-Kermadec subduction zone, which is usually divided into two arc systems, based of the presence of the Louisville Aseismic Ridge, located on the subducting Pacific plate.
A GPS survey of the Tonga Ridge has revealed that the rate of opening increases from south to north and that the Tonga Ridge shows little or no arc parallel deformation [Bevis et al., 1995], indicating that the latter model is most applicable.
www.virtualexplorer.com.au /2002/7/schellart/paper4.html   (2388 words)

  
 Slab pull effects from a flexural analysis of the Tonga and Kermadec trenches (Pacific Plate).   (Site not responding. Last check: 2007-10-20)
(1981) and Washbush and Royden (1992) to constrain the forces operating in the trench axis, the bending stress distribution and the thermal structureof the subducting lithosphere seawards of the Tonga and Kermadec trenches.These trenches are the topographic consequence of the subduction of thePacific oceanic plate (105 Ma old) under the Indo-Australian Plate (Fig.1).
Rather than taking a particular bathymetric transectacross the Tonga and Kermadec trenches, we have computed, for each studyarea, an average bathymetry profile that is representative of a wider regionof the plate seaward of both trenches (Fig.
is the mantle drag force acting between the trench and the ridge (positiveif opposite to the movement of the plate).
www.geo.vu.nl /~gard/papers/GJI/GJI9.html   (2799 words)

  
 Shock Dynamics: Oceanic Crust
Trenches (green line) along the leading edges of landmasses result from the rapid application of the weight of continental crust.
A crustal wave (red line) from the low angle impact was launched in the direction of travel of the meteorite, and "froze" in the end to form an inclined trench.
This group believes the Izu-Bonin-Mariana Trench formed on a former fracture zone or transform fault, and the Tonga-Kermadec Trench formed on an extinct subduction zone.
www.newgeology.us /presentation8.html   (1192 words)

  
 Tonga language resources
Y 2M has put Tonga on the map, since, thanks to a bend in the International Date Line, it will be the first country to greet it...
Tonga acquired its independence in 1970 and became a member of the Commonwealth of Nations.
Tonga Tonga is the language of the Tonga people who live in centran and southern Africa.
www.mongabay.com /indigenous_ethnicities/languages/languages/Tonga.html   (885 words)

  
 Cruise Plan
* Tonga is the type extensional convergent margin and is undergoing active tectonic erosion and its forearc is dominated by normal faulting and movement of material into trench and hence down subduction zone.
Previous experience has shown the trench slope assemblages to be diverse, talus samples; given the likely degree of normal faulting and downslope movement, long dredge tracks which give a representative sampling are of more use than short tracks used in a futile effort to determine a stratigraphy on the landward slope.
Eight additional dredges are allocated for shallow targets along the trench slope break that are suspected to be serpentinite diapirs.
sio.ucsd.edu /shipsked/schedules/1996/allships96/96MV/Bloomer/BloomerCruise.html   (1132 words)

  
 Samoa   (Site not responding. Last check: 2007-10-20)
Northward past the corner of the trench, I have curved it toward the west (along the Samoan post-erosional rift system) at the same distance from the trench at all points.
What happens to the bend as it rounds the curving corner of the trench is no doubt complicated, but subsidence west of the arch is well demonstrated by deformation of the Samoan apron south of Tutuila and the deep, rapid submergence of Machias Seamount.
Alternatively, thermal-convective disturbances triggered by trench rollback and the complex geometry of subduction at the curving corner of the trench may initiate diapir-like uprise of mantle material beneath this part of the Pacific Plate (Figure 3).
www.dur.ac.uk /maple.plumes/Samoa.html   (3423 words)

  
 Discover: Fastest trench in the West - subduction of seafloor in South Pacific is fastest ever recorded - Brief Article
The source of the speedy motion is the Lau Basin, a large chunk of seafloor that lies to the west of the trench, nestled in a V formed by two volcanic mountain chains, the Tonga Ridge and the Lau Ridge (see map on page 31).
The northern tip of the ridge, he and his colleagues determined, is moving east at six inches a year, while the Pacific plate is moving west at around three inches a year.
The turbocharged subduction at Tonga might explain an unusual characteristic of the zone: it produces most of the world's deep earthquakes--quakes originating at depths greater than 40 miles.
www.findarticles.com /p/articles/mi_m1511/is_n9_v16/ai_17199027   (586 words)

  
 Tonga Arc   (Site not responding. Last check: 2007-10-20)
GPS shows that the Tonga arc is moving rapidly toward the Pacific plate a little like a windshield wiper rotating clockwise.
The Tonga arc occupies a microplate separated from the Australian plate by seafloor spreading centers in the Lau Basin.
As Tonga moves eastward, the Pacific plate sinks or thrusts beneath the Tonga arc generating numerous earthquakes within the sinking Pacific plate.
www.ig.utexas.edu /research/projects/sw.pac.gps/fig3.html.old   (87 words)

  
 Tonga Trench -- Facts, Info, and Encyclopedia article   (Site not responding. Last check: 2007-10-20)
Tonga Trench -- Facts, Info, and Encyclopedia article
The Tonga trench is located in the (The largest ocean in the world) Pacific ocean and is 32,000 ft (9,900 m) deep.
The Tonga trench extends north-northeast from the (The smaller but more populous of two main islands of New Zealand; separated from South Island by Cook Strait) North Island of (An independent country within the British Commonwealth; achieved independence from the United Kingdom in 1907; known for sheep and spectacular scenery) New Zealand.
www.absoluteastronomy.com /encyclopedia/t/to/tonga_trench.htm   (181 words)

  
 Where It Starts   (Site not responding. Last check: 2007-10-20)
-The New Hebrides Trench extends from New Guinea to the east-southeast.
-The Kermadec Trench connects with the Tonga Trench to the north and the North Island of New Zealand to the south.
The other trenches on the map are mostly at sea, but two are on land.
home.earthlink.net /~dengelhardt/Starts.html   (284 words)

  
 Crustal motions in the Tonga-Lau Island Arc System   (Site not responding. Last check: 2007-10-20)
By comparing the relative position of a network of survey markers observed using GPS in 1990 and 1992 they determined the relative velocities of the earth's crust at these stations.
There is no evidence of longitudinal strain within the Tonga arc, suggesting that it acts like a rigid windshield wiper as it rotates to accommodate widening of the Lau Basin.
The new GPS results suggest that this intense seismic activity is a consequence of very rapid subduction of the Pacific plate at the Tonga trench.
www.wdcb.rssi.ru /~victat/GPS/press/paper_gps_1.html   (366 words)

  
 Tonga
This was the year of the infamous Tonga tie.
Being the person in charge of the on-air questions, I made absolutely sure that there was a Tonga question in there, because I was convinced that it was always that way.
Question: Tonga may be tiny, but it leads the whole, entire planet in at least one category.
wso.williams.edu /orgs/trivia/tonga.html   (2582 words)

  
 MELT Cruise Report   (Site not responding. Last check: 2007-10-20)
Fortuitously, this fast-spreading section of rise is located between two areas of active seismicity, the Tonga Trench and the South American subduction zone.
The Tonga Trench has a large fraction of the world's deep earthquakes, which are characterized by particularly simple source functions.
The seismic lines are aligned to point to the Tonga trench, a prolific source of earthquakes.
www-mpl.ucsd.edu /obs/reports/tn061/text.html   (2489 words)

  
 Tonga Trench Article, TongaTrench Information   (Site not responding. Last check: 2007-10-20)
The Tonga Trench and its forearc form an active convergent margin between two plates of the lithosphere, the Pacific Plate being subducted into the earth's semi-molten aesthenosphere, and the northeasterncorner of the Australian Plate overriding it.
The Tonga trenchextends north-northeast from the North Island of New Zealand.
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www.anoca.org /plate/taking/tonga_trench.html   (264 words)

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