The Ring of Fire is an area around the Pacific Ocean that traces the boundaries between several tectonic plates. Also referred to as the Circum-Pacific Belt, this path is approximately 25,000 miles long. It is the most seismically and volcanically active zone in the world, containing the majority of the planet’s earthquakes and volcanoes.
The Earth’s lithosphere, which includes the crust and upper mantle, is made up of a series of pieces, or tectonic plates. Below the lithosphere is the asthenosphere, which is malleable or partially malleable, allowing the lithosphere to move slowly over time. The Ring of Fire is a result of plate tectonics.
Plates around the world
There are a handful of major plates and dozens of minor plates around the world. Some of the major plates are named for the continents within them, such as the North American, African and Antarctic plates.
The largest plate is the Pacific Plate at 39,768,522 square miles. Most of it is located under the ocean. It is moving northwest at a speed of around 2.75 inches per year.
How plate tectonics works
Plate tectonics is driven by convection in the mantle. Hot material near the Earth’s core rises, and colder mantle rock sinks. This causes the plates to move at varying rates between 0 to almost 4 inches per year.
The movement of the plates creates three main types of tectonic boundaries: convergent, divergent, and transform. Most geologic activity, including earthquakes, volcanic activity, mountain building, and oceanic trench formation, stems from where the plates meet, called fault lines.
Convergent boundaries are where plates move into one another. These colliding plates can cause the edges of one or both plates to buckle up into a mountain range. If one of the plates is pushed down, it is called subjection. This can create a deep trench.
Divergent boundaries are where plates move apart. At divergent boundaries in the ocean, magma from the Earth’s mantle rises toward the surface and pushes apart plates. Mountains and volcanoes rise along the seam. On land, troughs form where plates are pulled apart.
Transform boundaries are where plates move sideways in relation to each other. Along these fault lines, stress builds up due to friction, which can trigger earthquakes.
Plates and the Ring of Fire
The abundance of volcanoes and earthquakes along the Ring of Fire is caused by the amount of movement of tectonic plates in the area.
The Ring of Fire traces boundaries between several tectonic plates, including the Pacific, Juan de Fuca, Cocos, Indian-Australian, Nazca, North American, and Philippine plates.
Many of these plates overlap at convergent boundaries. As rock is subducted, it melts and becomes magma. The abundance of magma so close to Earth’s surface creates ideal conditions for volcanic activity.
An exception to the area is the border between the Pacific and North American plates. This stretch of the Ring of Fire is a transform boundary that generates earthquakes as tension in Earth’s crust builds up and is released.
Most volcanoes are located where tectonic plates meet, especially along convergent boundaries, or subduction zones. When the heavier plate moves under another plate and melts, it produces magma that rises and erupts to the surface as a volcano.
The Ring of Fire is home to 75% of the world’s volcanoes, most of which can be found underwater.
Mount Tambora of Indonesia, which erupted in 1815 and became the largest volcanic eruption recorded in history, is located along the Ring of Fire.
The volcanoes found along the Pacific Northwest of the United States are mainly due to the tiny Juan de Fuca plate.
Along the Ring of Fire, there is a chain of volcanoes inland of each subduction zone called a volcanic arc. Alaska’s Aleutian Islands are an example of this.
Subduction zones are also where Earth’s deepest ocean trenches are located. The trenches form when one plate is bent downward as it subducts under another. The deepest point on Earth, the Mariana Trench, is located within the Ring of Fire. The 7-mile-deep trench can be found east of Guam.
The tectonic activity in the Ring of Fire results in about 90% of the world’s earthquakes, including the Valdivia Earthquake of Chile in 1960, which was the strongest recorded earthquake at 9.5 out of 10 on the Richter scale.
The size of an earthquake is related to the size of the fault that causes it, and subduction zone faults are the longest and widest in the world.
California’s San Andreas fault is a transform boundary where the North America and Pacific plates move past each other in a mostly horizontal motion. Tectonic movement along the fault has been associated with occasional large earthquakes, including a disastrous quake in San Francisco in 1906.
If an earthquake is large enough, it can generate a tsunami by suddenly moving the sea floor. However, not all earthquakes will cause tsunamis. Tsunamis may hit coastal areas in just minutes or hours later after the waves travel across the sea.