A convergent boundary is an area on Earth where two or more lithospheric plates collide. One plate eventually slides beneath the other, a process known as subduction. The subduction zone can be defined by a plane where many earthquakes occur, called the Wadati–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.
The Sunda Plate is a minor tectonic plate straddling the equator in the Eastern Hemisphere on which the majority of Southeast Asia is located.
The Solomon Sea is a sea located within the Pacific Ocean. It lies between Papua New Guinea and Solomon Islands. Many major battles were fought there during World War II.
A back-arc basin is a type of geologic basin, found at some convergent plate boundaries. Presently all back-arc basins are submarine features associated with island arcs and subduction zones, with many found in the western Pacific Ocean. Most of them result from tensional forces, caused by a process known as oceanic trench rollback, where a subduction zone moves towards the subducting plate. Back-arc basins were initially an unexpected phenomenon in plate tectonics, as convergent boundaries were expected to universally be zones of compression. However, in 1970, Dan Karig published a model of back-arc basins consistent with plate tectonics.
The 1,600 kilometres (990 mi) long Macquarie Fault Zone is a major right lateral-moving transform fault along the seafloor of the south Pacific Ocean which runs from New Zealand southwestward towards the Macquarie Triple Junction. It is also the tectonic plate boundary between the Australian Plate to the northwest and the Pacific Plate to the southeast. As such it is a region of high seismic activity and recorded the largest strike-slip event on record up to 23 May 1989, of at least 8.0
The Banda Sea Plate is a minor tectonic plate underlying the Banda Sea in southeast Asia. This plate also carries a portion of Sulawesi Island, the entire Seram Island, and the Banda Islands. Clockwise from the east it is bounded by the Bird's Head Plate of western New Guinea, Australian Plate, Timor Plate, Sunda Plate, and the Molucca Sea Collision Zone. The western border is a convergent boundary largely responsible for the mountains in western Sulawesi, subduction zones also exist on the eastern border near Seram and the southern border with the Timor Plate. A small rift is located in the middle of Sulawesi. It is a very seismically active area home to many volcanoes and the site of many large earthquakes, the largest of which was the 1938 Banda Sea earthquake which measured around 8.4 on the moment magnitude scale.
The Caroline Plate is a minor tectonic plate that straddles the Equator in the eastern hemisphere located north of New Guinea. It forms a subduction zone along the border with the Bird's Head Plate and other minor plates of the New Guinea region to the south. A transform boundary forms the northern border with the Pacific Plate. Along the border with the Philippine Sea Plate is a convergent boundary that transitions into a rift.
The Maoke Plate is a small tectonic plate located in western New Guinea underlying the Sudirman Range from which the highest mountain on the island- Puncak Jaya rises. To its east was proposed a convergent boundary with the Woodlark Plate, although this is now best modelled after further studies as a boundary with an enlarged Solomon Sea Plate or a new microplate called the Trobriand Plate. To the south lies a transform boundary with the Australian Plate and the Bird's Head Plate lies to the west.
The North Bismarck Plate is a small tectonic plate located in the Bismarck Sea off the northeast coast of New Guinea. It is currently regarded as a relic or inactive plate by most. At one time it was called the Manus Plate, but this term was later used for a modelled microplate at the south east boundary of the North Bismarck Plate.
The Okinawa Plate, or Okinawa Platelet, is a minor continental tectonic plate in the northern and eastern hemispheres stretching from the northern end of Taiwan to the southern tip of the island of Kyūshū. The Okinawa Plate hosts typical earthquakes, like the 1911 Kikai Island earthquake, and various types of slow earthquakes, including low frequency earthquakes, very low frequency earthquakes, tremor, and slow slip events.
The Shetland Plate, or South Shetland Plate, is a tectonic microplate located off the tip of the Antarctic Peninsula that contains the South Shetland Islands. The plate is bordered on three sides by the Antarctic Plate, while the fourth side is bordered by the Scotia Plate. The northwestern border is defined by the South Shetland Trench, separating the Shetland Plate to the south from the Antarctic Plate to the north. This trench is the remnant of a subduction zone where the defunct Phoenix Plate, now part of the Antarctic Plate, subducted under the Antarctic Peninsula and the Shetland Islands. The southeastern border is a rift zone, with the Antarctic Plate creating the Bransfield Basin. The southwestern and northeastern boundaries are each part of larger fracture zones. The southwestern border is the Hero Fracture Zone and separates the Antarctic Plate to the southwest from the Shetland Plate to the northeast. The northeastern boundary is the Shackleton Fracture Zone and separates the Shetland Plate to the southwest from the Scotia Plate.
The South Bismarck Plate is a small tectonic plate located mainly in the southern Bismarck Sea. The eastern part of New Guinea and the island of New Britain are on this plate. It is associated with high earthquake and volcanic activity as part of the New Britain subduction zone within the Pacific Ring of Fire.
The Solomon Islands (archipelago) is an island group in the western South Pacific Ocean, north-east of Australia. The archipelago is in the Melanesian subregion and bioregion of Oceania and forms the eastern boundary of the Solomon Sea. The many islands of the archipelago are distributed across the sovereign states of Papua New Guinea and Solomon Islands. The largest island in the archipelago is Bougainville Island, which is a part of the Autonomous Region of Bougainville along with Buka Island, the Nukumanu Islands, and a number of smaller nearby islands. Much of the remainder falls within the territory of Solomon Islands and include the atolls of Ontong Java, Sikaiana, the raised coral atolls of Bellona and Rennell, and the volcanic islands of Choiseul, Guadalcanal, Makira, Malaita, New Georgia, the Nggelas, Santa Isabel, and the Shortlands. The Santa Cruz Islands are not a part of the archipelago.
The Woodlark Plate is a small almost triangular shaped tectonic plate located east of the island of New Guinea and situated mainly within the northern half of the Woodlark Basin. It is located in a very complex tectonic environment, that because of associated features, has been extensively studied since it was first proposed to exist. It is now known to be much smaller than originally proposed, mainly because of information from GPS stations on islands and sea floor studies that have fully defined its margins.
The West Melanesian Trench is an oceanic trench in the Bismarck Sea north of Papua New Guinea delineating the plate tectonic boundary between the Caroline and North Bismarck plates.
The Kilinailau Trench is an oceanic trench delineating the former oceanic crust boundary between the Pacific Plate and the now inactive North Bismarck Plate, in the area to the west of Papua New Guinea. To its south west is the inactive North Solomon Trench. The collision of the Ontong Java Plateau in the then subducting oceanic crust of the Pacific Plate, initially to the trench's south-east, changed the plate collision dynamics relative to the then Indo-Australian Plate to the west. Now the Ontong Java Plateau is just to the east of the trench and its great depth of crust appears to explain why subduction stalled here, and moved to the opposite direction along the far side of New Britain and the Solomons. The Melanesian ocean arc ridge structures formed when the trench was active are to its west and would include the north eastern part of New Ireland.
The New Britain Trench has formed due to subduction of the floor of the Solomon Sea and has some of the highest current seismic activity in the world.
The Woodlark Basin is a young geologic structural basin located in the southwestern Pacific Ocean, found to the southeast of the island country of Papua New Guinea. The basin is an extensional basin that is actively spreading and has a seafloor spreading center. The basin formed between the then Indo-Australian Plate and the Solomon microplate creating the presently independent Woodlark Plate. The Woodlark Basin has a complex geologic history dating back twenty million years to the initial opening of the basin but most of the spreading has happened in the last 3.6 million years.
The Trobriand Plate was, and likely is, an independent microplate between New Guinea and the Solomon Islands. It has some unique geology, having the presence of the youngest metamorphic core complexes on earth. If there is presently active subduction between it and the Solomon Plate, at the Trobriand Trough, it continues to be an active microplate. Otherwise in the latest tectonic models it has merged with the Solomon Sea Plate, which becomes somewhat larger than predicted by Bird's 2003 model of Tectonic Plates. As a smaller Solomon Sea Plate is totally underwater, global positioning data can not resolve this issue. The area of the plate is associated with earthquake and volcanic activity as part of the Pacific Ring of Fire.
The New Britain subduction zone is one of the most recently formed and most active subduction zones on earth, producing great earthquakes, with potential for tsunami hazard, and being associated with active volcanism, as part of the Pacific Ring of Fire. It has a close relationship to an area of subduction tectonic activity that extends south eastward from New Britain to the Vanuatu subduction zone, involving the north eastern portion of the Australian Plate and its complicated collision dynamics with the south-western portion of the Pacific Plate.
