The [Pacific] plate first came into existence as a microplate 190 million years ago, at the triple junction between the Farallon, Phoenix, and Izanagi Plates.
The boundary between Okhotsk microplate and Pacific plate is a subduction zone, where the Pacific plate subducts beneath the Okhotsk Plate.
In the Early Jurassic the Pacific Plate opened originating from a triple junction between the Panthalassic Farallon, Phoenix, and Izanagi plates.
For the most part, the North American Plate moves in roughly a southwest direction away from the Mid-Atlantic Ridge at a rate of about 2.3 centimeters (~1 inch) per year. At the same time, the Pacific Plate is moving to the northwest at a speed of between 7 and 11 centimeters (~3-4 inches) a year.
Pacific Plate (Wikipedia) The Pacific Plate is an oceanic tectonic plate that lies beneath the Pacific Ocean. At 103 million km2 (40 million sq mi), it is the largest tectonic plate.
