Though the Pacific Ocean is very old, but the Pacific Plate is comparatively young. It is believed that probably there was an ocean situated in the present day position of the Pacific Ocean for a period of nearly a billion years. The Pacific Ocean basin first originated when the western half of North America rifted from the eastern coasts of Australia and Antarctica, about 750 million years ago. The rifting of Rodinia – the Precambrian supercontinent produced the Panthalassic Ocean. The plates which led to the formation of Panthallasic Ocean basin have been subducted. The present Pacific plate was formed about 180 million years ago. The Pacific, Farallon, Kula and Izanagi plates grew rapidly, though it is still not clear how the Pacific rift started. Presently, the plate is shrinking as the Atlantic Ocean is increasing in size, and is pushing the North American Plate slowly towards the west.
The Pacific Plate is roughly 103,300,000 sq. km, with an estimated absolute velocity of about 8.10 cm. The Pacific Ocean being large covers about one-third of the Earth. Both New Zealand and Japan are on the western side of it. Japan is situated along the western edge of the Ring of Fire – a zone which is prone to frequent volcanic activities and earthquakes that encircles the Pacific Ocean.
The Ring of Fire basically is a region comprising high volcanic activities and earthquakes which surround the major portion of the Pacific Ocean Basin. In shape, it is similar to a horseshoe and is associated with deep seep trenches, earthquakes, volcanoes and major fault zones. Being 40,000 km long, it touches four of the world’s continent and some of the major island chains. It is made of the plate boundaries which border the Pacific Ocean basin. The ring of fire consists of 452 volcanoes and 75% of the world’s most active volcanoes. It is also sometimes referred as the circum-Pacific belt or the circum-Pacific seismic belt.