The Pacific Ring of Fire: why most earthquakes happen around the Pacific
The Ring of Fire is a horseshoe-shaped belt about 40,000 km long around the edge of the Pacific Ocean. It hosts most of the world's earthquakes and a large share of its active volcanoes.
Where it runs
Starting at the southern tip of South America, the ring follows the Andes north, continues up Central America, Mexico and the west coast of the United States and Canada, crosses Alaska and the Aleutian Islands, and comes down through Kamchatka, Japan, the Philippines and Indonesia to Papua New Guinea, Tonga and New Zealand.
See it on the map → See a full year of M4.5+ earthquakes over the Pacific, with plate boundaries and volcanoes. The quakes outline the ring.Why the Pacific?
The Pacific Ocean is ringed by subduction zones. On almost every side, ocean plates such as the Pacific, Nazca, Cocos and Philippine Sea plates sink beneath the plates around them. Subduction produces both earthquakes and volcanoes, so the Pacific rim is lined with both.
Not every part of the ring is subduction. Along California the Pacific and North American plates slide past each other on the San Andreas Fault, which causes shallow earthquakes but few volcanoes.
How many earthquakes?
Around 90% of the world's earthquakes, and most of the largest ones, happen along the Ring of Fire. The other main earthquake belt runs from the Mediterranean through Turkey, Iran and the Himalayas to Indonesia, where the African, Arabian and Indian plates push into Eurasia.
See it on the map → Compare the Mediterranean–Himalayan belt.Deep quakes are a Ring of Fire feature
Because deep earthquakes only happen in sinking slabs, nearly all of them are on the Ring of Fire. The Atlantic Ocean, by contrast, has very few subduction zones. Its mid-ocean ridge produces only shallow quakes, so the Atlantic stays almost completely yellow on a depth map.
See it on the map → Look at the shallow quakes along the Mid-Atlantic Ridge.