Where it is and what it carries
The Woodlark Plate covers about 453,000 km² of eastern New Guinea and the nearby seas. In the PB2002 model it holds about 46% of Papua New Guinea, including the Papuan Peninsula with the Owen Stanley Range, much of the central highlands and part of the north coast near Aitape. A small slice of Indonesia also sits on it. Offshore it includes the D’Entrecasteaux and Trobriand islands and reaches east toward the Solomon Islands.
The plate is part of a tangle of microplates that formed as the northern edge of the Australian Plate collided with island arcs on the edge of the Pacific. Geologists separate it from Australia because the Woodlark Basin spreading ridge clearly divides the two.
A continent splitting into an ocean
The 2,205 km boundary with the Australian Plate is the plate’s longest and most varied. In the east it is a true spreading ridge in the Woodlark Basin, where new oceanic crust forms. Toward the west, the ridge runs into the continental crust of the Papuan Peninsula and becomes a rift. Relative speeds range from about 1 cm/yr in the west to about 4 cm/yr in the east, which fits a plate spinning about a pole near its western end. Farther west, in the Papuan fold belt, the two plates converge instead.
The D’Entrecasteaux Islands sit just ahead of the westward-growing rift. Their mountains are domes of deep crustal rock pulled up as the crust thinned.
Other edges
To the north, the Solomon Sea Plate sinks slowly beneath the Woodlark Plate along the Trobriand Trough, at about 1.3 cm/yr. The boundary with the South Bismarck Plate mixes collision, rifting and strike-slip faulting along the Ramu and Markham valleys, at about 3.5 cm/yr on average. In the west it collides with the Maoke Plate at about 2.6 cm/yr, and off the north coast it has a subduction boundary with the Caroline Plate, where relative motion is about 7 cm/yr.
At its eastern tip, the plate meets the North Bismarck Plate and the Pacific Plate along short subduction segments, at about 7.8 and 10.5 cm/yr. Near the New Georgia Islands, the Woodlark Basin’s own spreading ridge is being carried into the trench. A 54 km segment also touches the Bird’s Head Plate.
Earthquakes and volcanoes
The dataset lists 48 earthquakes of magnitude 6.5 or larger since 1900, none reaching magnitude 8. The largest was an M7.8 quake in 1935 near the north coast of New Guinea. An M7.6 quake struck near Aitape in 2002, and in 2018 an M7.5 quake hit the highlands near Tari, setting off landslides across the fold belt. An M7.5 quake in 1963 struck 187 km deep near Wau.
Seven volcanoes sit on the plate. Mount Lamington erupted violently in 1951. Mount Victory and the Dawson Strait Group, in the D’Entrecasteaux Islands, are also listed as active.