Small tectonic plate in the Bismarck Sea north of New Guinea
North Bismarck Plate
The relationships of the presently inactive North Bismarck Plate (red shading). While the map relates to a 2003 model where it was proposed to be still active, it is reasonably accurate compared to current understanding.[1][2]
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.[3][2] 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.[1]: 22
Tectonics
The plate contains most of the Melanesian arc volcanoes, related to current and historic arc volcanism, except those of
New Britain which are on the active
South Bismarck Plate.[2]
To the north it has collided with the
Pacific Plate and the
Caroline Plate, part of the western part is subducting under other active plates in
New Guinea, and it is separated from the South Bismarck Plate by a
divergent boundary called the Bismarck Seismic Sea Lineation (BSSL).[4] The BSSL is a very seismically active area but the assigned shallow earthquakes tend to be less than magnitude 7.[5] The plate is moving westerly along with the
Pacific Plate.[2] Between the plate and the
Caroline Plate is the
West Melanesian Trench and between the plate and the Pacific plate is the
Kilinailau Trench.[2] Neither trench has good evidence for current subduction activity but were certainly historically active.[2]: 68 There are a few shallow low intensity earthquakes to the south/south west of these trenches on a line of the old arc that extends from the smaller northern Admiralty Islands in the west through to
Mussau Island and beyond.[6]
^
abcdefHolm, RJ; Rosenbaum, G; Richards, SW (1 May 2016). "Post 8 Ma reconstruction of Papua New Guinea and Solomon Islands: Microplate tectonics in a convergent plate boundary setting". Earth-Science Reviews. 156: 66–81.
doi:
10.1016/j.earscirev.2016.03.005.
^Weiler, PD; Coe, RS (2000). "Rotations in the actively colliding Finisterre Arc Terrane: paleomagnetic constraints on Plio-Pleistocene evolution of the South Bismarck microplate, northeastern Papua New Guinea". Tectonophysics. 316 (3–4): 297–325.
doi:
10.1016/S0040-1951(99)00259-0.