Tonga Plate

The Tonga Plate is a small southwest Pacific tectonic plate or microplate. It is centered at approximately 19° S. latitude and 173° E. longitude. The plate is an elongated plate oriented NNE - SSW and is a northward continuation of the Kermadec linear zone north of New Zealand. The plate is bounded on the east and north by the Pacific Plate, on the northwest by the Niuafo’ou Microplate, on the west and south by the Indo-Australian Plate. The Tonga plate is subducting the Pacific plate along the Tonga Trench. This subduction turns into a transform fault boundary north of Tonga. An active rift or spreading center separates the Tonga from the Australian plate and the Niuafo’ou microplate to the west. The Tonga plate is seismically very active and is rotating clockwise.

These were the plates that moved when the 2009 tsunami hit Samoa.

See also

  • Tonga-Kermadec Ridge – An oceanic ridge in the south-west Pacific Ocean underlying the Tonga-Kermadec island arc

References

  • Bird, P., An updated digital model of plate boundaries, Geochem. Geophys. Geosyst., 4(3), 1027, doi:10.1029/2001GC000252, 2003.
1917 Samoa earthquake

The 1917 Samoa earthquake occurred on June 26 at 05:49 UTC. The epicenter was located in the southwest of the Samoan Islands. The earthquake had a magnitude of Mw 8.5, or Ms 8.4, one of the strongest earthquakes ever recorded in this region.Many subsidences were reported. In the mountains, masses of rocks were hurled down. In Apia, violent shaking lasted for about a minute and half. In American Samoa, the LDS Church in Pago Pago and the Catholic Church in Leone were partly demolished. A tsunami was triggered by the earthquake, which affected both American Samoa and German Samoa, which was then under Allied occupation. The tsunami reached a maximum of 40 feet. The maximum range of the tsunami in Apia was about 80 cm. Many houses were destroyed, and a bridge was washed away in Palauli. The tsunami was also recorded in Honolulu and on the west coast of the United States. Just on May 1, 1917, a large earthquake of magnitude Ms  8.0 occurred in the Kermadec Islands region. The tsunami caused by the earthquake in May also hit the Samoan Islands.The earthquake occurred to the southwest of the Samoa Islands, along the Tonga Plate boundary. The focal mechanism of this earthquake was unclear. This earthquake and the 2009 event were not thought to represent the same repeating process in a same location.

2006–07 IRB Sevens World Series

2006–07 IRB Sevens World Series was the eighth of an annual series of rugby sevens tournaments for full national sides run by the International Rugby Board since 1999–2000.

New Zealand won the 2006–07 series by winning the final tournament in Edinburgh. In that event, the then-defending series champions Fiji would have clinched the season crown by defeating Wales in the Cup quarterfinals. However, a Wales upset win opened the door for New Zealand to take the season crown by winning the Cup in Edinburgh, which they did.

Sevens is traditionally played in a two-day tournament format; however, the most famous event, the Hong Kong Sevens, is played over three days.

2007–08 IRB Sevens World Series

The 2007–08 IRB Sevens World Series was the ninth of an annual IRB Sevens World Series of rugby sevens tournaments for full national sides run by the International Rugby Board since 1999–2000.

The defending series champions, New Zealand, dominated this season's competition, winning the first five events, setting new records for consecutive tournament wins and consecutive match wins, and clinching the 2007–08 series with one tournament remaining after winning the Plate Final of the London leg. They ended with six wins out of the eight events.

Sevens is traditionally played in a two-day tournament format; however, the most famous event, the Hong Kong Sevens, is played over three days.

2010 Oceania Sevens Championship

The 2010 Oceania Sevens Championship was the third Oceania Sevens in men's rugby sevens. It was held at Larrakia Park (also known as Austar Rugby Park) in Darwin, Northern Territory, Australia.Australia won the Oceania Sevens Championship by defeating Samoa 34 to 12. Tonga, PNG and the Cook Islands, as the three highest finishers excluding core teams Australia and Samoa, qualified for the Wellington and Adelaide legs of the 2010–11 IRB Sevens World Series. Tonga also qualified for the 2011 Hong Kong Sevens.

2011 Oceania Sevens Championship

The 2011 Oceania Sevens Championship was the fourth Oceania Sevens in men's rugby sevens. It was held at Apia Park in Samoa.Samoa won the Oceania Sevens Championship by defeating Fiji 19 to 7. Tonga, PNG and Niue, as the three highest finishers excluding core teams Australia, Fiji and Samoa, qualified for Gold Coast legs of the 2011–12 IRB Sevens World Series. Tonga also qualified for the 2012 Hong Kong Sevens.

2012 Oceania Sevens Championship

The 2012 Oceania Sevens Championship was the fifth Oceania Sevens in men's rugby sevens. It was held at North Sydney Oval in Sydney, Australia. The winner qualified through to the 2013 Rugby World Cup Sevens tournament in Moscow.

Australia won the Oceania Sevens Championship by defeating Samoa 12-7.

Convergent boundary

A convergent boundary is an area on Earth where two or more lithospheric plates collide. One plate eventually slides beneath the other causing a process known as subduction. The subduction zone can be defined by a plane where many earthquakes occur, called the Benioff Zone. These collisions happen on scales of millions to tens of millions of years and can lead to volcanism, earthquakes, orogenesis, destruction of lithosphere, and deformation. Convergent boundaries occur between oceanic-oceanic lithosphere, oceanic-continental lithosphere, and continental-continental lithosphere. The geologic features related to convergent boundaries vary depending on crust types.

Plate tectonics is driven by convection cells in the mantle. Convection cells are the result of heat generated by radioactive decay of elements in the mantle escaping to the surface and the return of cool materials from the surface to the mantle. These convection cells bring hot mantle material to the surface along spreading centers creating new crust. As this new crust is pushed away from the spreading center by the formation of newer crust, it cools, thins, and becomes denser. Subduction initiates when this dense crust converges with the less dense crust. The force of gravity helps drive the subducting slab into the mantle. Evidence supports that the force of gravity will increase plate velocity. As the relatively cool subducting slab sinks deeper into the mantle, it is heated causing dehydration of hydrous minerals. This releases water into the hotter asthenosphere, which leads to partial melting of asthenosphere and volcanism. Both dehydration and partial melting occurs along the 1000 °C isotherm, generally at depths of 65 – 130 km.Some lithospheric plates consist of both continental and oceanic lithosphere. In some instances, initial convergence with another plate will destroy oceanic lithosphere, leading to convergence of two continental plates. Neither continental plate will subduct. It is likely that the plate may break along the boundary of continental and oceanic crust. Seismic tomography reveals pieces of lithosphere that have broken off during convergence.

Geology of the Pacific Ocean

The Pacific Ocean evolved in the Mesozoic from the Panthalassic Ocean, which had formed when Rodinia rifted apart around 750 Ma. The first ocean floor which is part of the current Pacific Plate began 160 Ma to the west of the central Pacific and subsequently developed into the largest oceanic plate on Earth.The tectonic plates continue to move today. The slowest spreading ridge is the Gakkel Ridge on the Arctic Ocean floor, which spreads at less than 2.5 cm/year (1 in/year), while the fastest, the East Pacific Rise near Easter Island, has a spreading rate of over 15 cm/year (6 in/year).

Kermadec-Tonga subduction zone

The Kermadec-Tonga subduction zone is a convergent plate boundary that stretches from the North Island of New Zealand northward. The formation of the Kermadec and Tonga Plates started about 4–5 million years ago. Today, the eastern boundary of the Tonga Plate is one of the fastest subduction zones, with a rate up to 24 cm/yr. The trench formed between the Kermadec-Tonga and Pacific Plates is also home to the second deepest trench in the world, at about 10,800 m, as well as the longest chain of submerged volcanoes.

List of tectonic plates

This is a list of tectonic plates on the Earth's surface. Tectonic plates are pieces of Earth's crust and uppermost mantle, together referred to as the lithosphere. The plates are around 100 km (62 mi) thick and consist of two principal types of material: oceanic crust (also called sima from silicon and magnesium) and continental crust (sial from silicon and aluminium). The composition of the two types of crust differs markedly, with mafic basaltic rocks dominating oceanic crust, while continental crust consists principally of lower-density felsic granitic rocks.

Niuafo'ou Plate

The Niuafo'ou Plate is a small tectonic plate located west of the islands of Tonga. This plate is sandwiched between the Pacific Plate to the north, the very unstable Tonga Plate to the east and the Australian Plate to the west. It is primarily surrounded by convergent boundaries. This plate is riddled with active faults thus making the area extremely earthquake prone.

Tonga Trench

The Tonga Trench is an oceanic trench located in the south-west Pacific Ocean. It is the deepest trench of the Southern Hemisphere and the second deepest on Earth. The fastest plate tectonic velocity on Earth occurs as the Pacific Plate is being subducted westward in the trench.

When the Apollo 13 mission was aborted in 1970 following an explosion in an oxygen tank, the radioisotope thermoelectric generator broke up in the atmosphere and the heat source plunged in or near the Tonga Trench. Atmospheric and oceanic monitoring indicate no release of nuclear fuel has occurred.

Tonga women's national rugby sevens team

The Tongan women's national sevens team represents Tonga in rugby sevens.

The team has played at the 2010 and 2011 Asia-Pacific Championship, the Oceania Women's Sevens Championship since 2012, and the 2015 2015 Pacific Games.They won the Bowl final at the 2011 Borneo Women’s Sevens competition which included teams from Asia and the Oceanic region.

ʻEua

ʻEua is a smaller but still major island in the kingdom of Tonga. It is close to Tongatapu, but forms a separate administrative division. It has an area of 87.44 km2 (33.76 sq mi), and a population in 2011 of 5,016 people.

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