You may think of the Earth as being solid beneath your feet, but it is really made up of a series of "plates." These sections of the planet's crust are constantly moving, though very slowly. The rubbing of their edges causes earthquakes and volcanoes. Together, they make up the part of the earth called the "lithosphere."
The largest of the tectonic plates lies beneath the largest ocean. The Pacific Plate covers 64,175,216.7 square miles, according to Los Alamos National Laboratory geophysicists W.K. Brown and K.H. Wohletz. The largest continental plates each cover parts of two continents. The vast North American Plate reaches from the mid-Atlantic to the West Coast, with a northern boundary that curves further west to include many miles of Siberia. It is 47,154,617 square miles. The Eurasian continent, which borders it at both east and west, covers 42,135,801.9 square miles.
Other Continental Plates
The African Plate, which also includes much of the Atlantic and Indian oceans, covers 38,111,180.7 square miles, according to Brown and Wohletz. Next in size is the Antarctic Plate, which caps the South Pole with its 37,851,447.5 square miles. The Australian Plate meets the Pacific Plate near New Zealand and Indonesia and covers 29,298,894.45 square miles. The South American Plate stretches from the Andes to meet the African Plate in the mid-Atlantic and covers 27,102,347.3 square miles.
Among the mid-size plates, the largest is the Nazca Plate, off the western coast of South America, at 9,712,031.7 square miles. The subcontinent of India lends its name to another secondary tectonic plate, which borders the Eurasian Plate along the Himalayan Mountains. It covers 7,406,744.6 square miles. The Philippine Plate, 3,384,608.8 square miles, is part of the geologically active "Ring of Fire" bordering the Pacific Ocean. Nearly as large is the Arabian Plate, at 3,113,628.9 square miles.
Smaller, or tertiary plates, can nonetheless play an important role in earthquakes, tsunamis and volcanoes. An example is the active Juan de Fuca Plate, off the coast of the U.S. Pacific Northwest, which is only 156,585.5 square miles. Other smaller plates include the Caribbean at 2,062,330.98 square miles, Cocos at 1,777,121.6 square miles and Scotia at 1,025,883.8 square miles.
- National Geographic: Plate Tectonics: Moving and Shaking
- U.S. Geological Survey; This Dynamic Earth: Dynamic Slabs; November 2008
- Los Alamos National Laboratory; Sequential Fragmentation/Transport and the World's Tectonic Plates; W.K. Brown and K.H. Wohletz
- U.S. Geological Survey Cascades Volcano Observatory; Juan de Fuca Volcanics
- Photo Credit Thinkstock/Comstock/Getty Images