The world’s largest sea sits on its own tectonic plate
East of the Philippines, the Philippine Sea covers an estimated five million square kilometres—the largest sea on Earth—floored by the Philippine Sea Plate. Island arcs from the Ryukyus and Taiwan to the Marianas and Palau fence it in, while Japan bounds the north.
Faults and fracture zones carve the floor into a structural basin, and ridges pushed up by plate motion break the surface as island arcs that enclose the sea to the north, east and south. Westward lie the Philippines and Taiwan, southward Palau, eastward the Marianas. Deep trenches score the floor, among them the Philippine Trench and the Mariana Trench, which holds the lowest point on the planet.
The International Hydrographic Organization places the sea in the North Pacific off the eastern Philippine coasts. Its western edge follows the limits of the East Indian Archipelago and the South and East China seas; its northern edge runs along south-eastern Kyushu, the Inland Sea and Honshu’s southern shore; its eastern edge follows the ridge from Japan through the Bonin, Volcano and Mariana islands; and its southern edge is a line through Guam, Yap, Palau and Halmahera. Beyond lie the Celebes Sea past Mindanao and the China seas across the archipelago and the Ryukyus.
Along the Philippine Trench the Philippine Sea Plate dives beneath the Philippine Mobile Belt. The Philippines claims more than 679,800 square kilometres of marine territory and an exclusive economic zone of about 2.2 million.
Those waters sit at the apex of the Coral Triangle, a roughly two-million-square-kilometre zone reaching across Indonesia, Malaysia, the Philippines, Papua New Guinea, Timor-Leste and the Solomon Islands that is regarded as the world centre of marine biodiversity. It holds about three-quarters of all coral species, more than 2,000 kinds of reef fish and six of the seven marine turtle species. Philippine reefs alone host over 500 stony coral species, at least 12 found nowhere else, and researchers mostly credit tectonics for the richness.
Source: Philippine Sea
