South Bismarck plate | |
---|---|
Type | Minor |
Movement1 | north-east |
Speed1 | 26mm/year |
Features | Pacific Ocean |
1Relative to the African 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.
Convergent boundaries line the southern border including the New Britain subduction zone that contributed to the formation of New Britain and the Solomon Islands. Many earthquakes occur in this area particularly around New Britain, [3] [4] [5] which has very complex tectonics and defining all the active plate boundaries has proved challenging. [6] [7] To the south of the South Bismark Plate is the Solomon Sea Plate which is subducting under New Britain at the New Britain Trench and a likely still active Trobriand Plate which has fault zone relationships at the postulated plate boundary. [2]
GPS data shows the South Bismarck plate, though north of the Australian plate boundary, is being pushed by Australia in a northerly direction while the area of the historic North Bismarck Plate is being dragged or pushed by the Pacific Plate to the west. [8] The North Bismark Plate does not have detectable independent motion to the Pacific Plate and most believe it to be a relic plate. [9] Accordingly as the west-northwest motion of the North Bismarck microplate is similar to that of the Pacific plate, most of the Melanesian arc which is to the east of the New Ireland can be regarded as fixed on the Pacific Plate. [10] The line separating the North and South Bismarck Plates is called the Bismarck Sea Seismic Lineation (BSSL), and this line is ill-defined, but is associated with shallow earthquakes, [5] with poor definition of BSSL associated earthquakes that become mixed with subduction associated earthquakes towards the southwest and New Ireland. [8] [11] These subduction associated earthquakes, unlike at the other plate boundaries, are often magnitude 7 or above and the area around southern New Ireland has a very high concentration of such. [4]
The plate boundaries to the east, mainly within New Guinea are also complex, although as for all the postulated plate boundaries, current shallow earthquake activity acts as a guide. [5] New Guinea's Finistree Block is usually mapped into the plate. [4] [9]
The Okhotsk microplate is a proposed minor tectonic plate covering the Kamchatka Peninsula, Magadan Oblast, and Sakhalin Island of Russia; Hokkaido, Kantō and Tōhoku regions of Japan; the Sea of Okhotsk, as well as the disputed Kuril Islands.
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.
The Solomon Sea Plate is a minor tectonic plate to the northwest of the Solomon Islands archipelago in the south Pacific Ocean. It roughly corresponds with the Solomon Sea east of Papua New Guinea. The plate boundaries are associated with high earthquake activity as part of the New Britain subduction zone.
The New Hebrides Plate, sometimes called the Neo-Hebridean Plate, is a minor tectonic plate located in the Pacific Ocean. While most of it is submerged as the sea bottom of the North Fiji Basin, the island country of Vanuatu, with multiple arc volcanoes, is on the western edge of the plate. It is bounded on the south-west by the Australian Plate, which is subducting below it at the New Hebrides Trench. The Vanuatu subduction zone is seismically active, producing many earthquakes of magnitude 7 or higher. To its north is the Pacific Plate, north-east the Balmoral Reef Plate and to its east the Conway Reef Plate.
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 Balmoral Reef Plate is a small tectonic plate (microplate) located in the south Pacific north of Fiji. Clockwise from the north, it borders the Pacific Plate, the Australian Plate, Conway Reef Plate, and the New Hebrides Plate. The northern and western borders are a divergent boundary while the rest of the borders are transform and convergent boundaries. The Balmoral Reef Plate's ocean crust is less than 12 million years old and is spreading between the New Hebrides and Tonga subduction. The plate forms the west central part of the seafloor of the North Fiji Basin.
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 Manus Plate is a 100-km microplate located northeast of New Guinea. The Manus Plate was formed in between the North Bismark Plate and the South Bismark Plate. The Manus Plate currently rotates counter-clockwise in the Melanesia area.
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 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 2000 New Ireland earthquakes occurred off the coast of New Ireland Province, Papua New Guinea on November 16 and 17.
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.
The New Guinea Trench is a trench along the northern coast of New Guinea. It may represent the seafloor expression of an active subduction zone.
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