Where it is and what it carries
The Pacific Plate covers about 104.6 million square kilometers, or 20.5% of Earth’s surface. That makes it larger than any other plate in the PB2002 model. It stretches from the Aleutian Islands in the north to the Pacific-Antarctic Ridge in the south, and from Japan and New Zealand in the west to the East Pacific Rise in the east.
Nearly all of it is oceanic crust. The main exceptions are thin continental slivers on its eastern and southwestern edges: coastal California west of the San Andreas Fault, the Baja California peninsula of Mexico, and the part of New Zealand east of the Alpine Fault, including Christchurch. Many island nations sit entirely on the plate, among them Samoa, Kiribati, the Marshall Islands, Tuvalu and French Polynesia.
What happens at its edges
The eastern edge is a spreading ridge. Along the East Pacific Rise, the Pacific Plate separates from the Nazca Plate at about 14 cm/yr on average, one of the fastest spreading rates on Earth. It also spreads away from the Cocos Plate at about 10 cm/yr and from the Antarctic Plate at about 7.3 cm/yr along the Pacific-Antarctic Ridge.
In the northeast, the plate meets the North American Plate along a boundary 8,341 km long that changes character as it goes. In California it is a transform fault, the San Andreas. Off Alaska it becomes the Aleutian Trench, where the Pacific Plate subducts. The average relative speed along this boundary is about 5.6 cm/yr. Farther south, the small Juan de Fuca Plate spreads away from it at about 5.6 cm/yr.
The western edge is almost all subduction. The plate dives under the Okhotsk Plate at the Kuril-Kamchatka and Japan trenches (about 8.7 cm/yr), under the Philippine Sea Plate at the Izu-Bonin Trench (about 4.2 cm/yr) and under the Mariana Plate at the Mariana Trench (about 6.3 cm/yr). The fastest convergence in the data is at the Tonga Trench, where the Pacific Plate meets the Tonga Plate at about 19 cm/yr on average and up to 26 cm/yr. Old, cold Pacific seafloor is dense, which helps explain why it sinks so readily.
In the southwest, the boundary with the Australian Plate runs through New Zealand as the Alpine Fault, a continental transform that lifts the Southern Alps.
Hotspots and the Hawaiian chain
Far from any edge, the Pacific Plate carries the Hawaiian Islands. Kilauea and Mauna Loa, which last erupted in 2022, sit above a mantle hotspot. As the plate moves, each volcano drifts off the hotspot and goes extinct, leaving a line of islands and seamounts that get older toward the northwest. A sharp bend in this line, where the Hawaiian Ridge meets the Emperor Seamounts, records a change in the plate’s direction about 47 million years ago. The plate holds 43 volcanoes in the dataset, including arc volcanoes in the Solomon Islands such as Tinakula and Kavachi.
Earthquakes on the plate
The dataset records 390 earthquakes of magnitude 6.5 or larger on the Pacific Plate since 1900, eight of them magnitude 8 or larger. The largest is the 1933 Sanriku earthquake off Japan (M8.4), which broke the Pacific Plate itself as it bent down into the Japan Trench. Others include the 1917 Kermadec Islands earthquake (M8.2), the 2007 Solomon Islands earthquake (M8.1) and the 2009 Samoa earthquake (M8.1).
Many famous subduction quakes, such as the 1964 Alaska and 2011 Tohoku earthquakes, involve the Pacific Plate but have epicenters on the overriding plate. They are counted on the North American and Okhotsk plate pages.