Earth

What is Earth’s Ring of Fire?

A volcanic eruption at night with red lava spewing from the volcano, with a backdrop of stars on a clear night.
The Fuego Volcano, in Antigua, Guatemala, is one of Central America’s most active volcanoes, and is a part of the Ring of Fire. This spectacular eruption was captured on March 28, 2017. Image via Travicted Photography / Flickr.

Most of Earth’s volcanoes and earthquakes are found in regions that skirt the Pacific Ocean, known as the Ring of Fire. It’s not really a ring, though, but more of a horseshoe-shaped swath – 24,900 miles (40,000 km) long – dotted with seismically active locations.

A map of the continents tracing out the Ring of Fire in red. Also marked in blue are the locations of subduction zones.
View larger. | The Ring of Fire is an almost horseshoe-like region on Earth where the boundaries of tectonic plates meet. The plate interactions result in a high incidence of volcanoes and earthquakes. Image via Gringer / Wikimedia Commons.

If you could view it from space, the Ring of Fire would appear as a strip that runs up the western coasts of South America and North America, continuing across the Alaskan Aleutian Islands to Russia’s Kamchatka Peninsula. Then, it heads south, off the coast of Eastern Asia, passing through Japan. At Southeast Asia, it jogs eastward through the Indonesian islands of Sumatra and Java, past Papua New Guinea, then southward again to New Zealand.

Volcanoes

Geologists have found evidence of prehistoric volcanoes, almost 1,000 of them, along the Ring of Fire that were active in the past 12,000 years. During this period, the four largest volcanic eruptions on our planet occurred in Alaska, Japan, Russia, and the US.

A world map showing the locations of currently active volcanoes. Most are along the Ring of Fire.
According to the Smithsonian Institution’s Global Volcanism Program, as of May 6, 2021, there are 47 volcanoes erupting around the world. As you’ll note in this figure, most are along the Ring of Fire. Image via Smithsonian Institution.

The iconic Mt. Fuji of Japan is in one of several volcanic chains that make up the Ring of Fire. It has been relatively quiet in recent years, with just minor eruptions.

In contrast, Mount St. Helen’s eruption in 1980 shocked the world. It was the most significant volcanic eruption in US history, causing a catastrophic explosion that resulted in the largest known landslide recorded and an ash plume that reached 80,000 feet. The explosion obliterated the surrounding 230 square miles in minutes.

Meanwhile, along the Ring of Fire, there’s always something happening, volcanically speaking … The Pacaya Volcano in Guatemala made the news in April 2021 following a series of eruptions that created wildfires and destroyed nearby plantations.

In April 2020, a volcano named Anak Krakatau caused a lot of excitement on social media and the news with dramatic new eruptions. It emerged from the caldera of the infamously violent Krakatoa volcanic explosion of 1883

New land also continues to be created in the Ring of Fire. A young volcano is making itself known off the coast of Japan. The Nishinoshima volcano has been growing since 2013, and underwent a growth spurt in June 2020.

Earthquakes

About 90% of all earthquakes, and 80% of the largest ones, occur in the Ring of Fire. Since the invention of equipment to measure earthquake intensity in the 1930s, four of the most powerful earthquakes have occurred in the Ring of Fire. In 1952, a magnitude 9.0 earthquake struck the Kamchatka Peninsula of Russia. Chile’s Valdivia earthquake in 1960 was a stunning 9.4 to 9.6 on the Richter scale. Four years later, a magnitude 9.2 earthquake hit Alaska.

A map of the world marking locations of major earthquakes, shown as colored dots. Most are along the Ring of Fire.
A compilation of major earthquakes across the world, shown in dots, from 1900 to 2013. The size of the dot corresponds to the earthquake’s magnitude, while color indicates depth. Also noted, in yellow triangles, are the locations of volcanoes. Click on this link for a larger view. Image via Masaqui / Wikimedia Commons.

And, more recently, the 2011 Tohoku Earthquake in Japan has become seared in our memories. The world watched, horrified, as large stretches of coastal land, including communities, near Sendai, Japan were engulfed in a tsunami that was triggered by an offshore earthquake. It caused widespread death, destruction, and lead to the serious breach of a nuclear reactor.

Why is the Ring of Fire so seismically active?

Volcanoes and earthquakes most often occur along the borders of tectonic plates. These plates are layers of the Earth’s crust that float — moving very slowly — on molten rock in Earth’s mantle.

The Ring of Fire is not a single geological feature, but actually separate adjoining features caused by interactions of several different tectonic plates. Where the two plates meet, in what’s called a subduction zone, the heavier plate sinks below the lighter plate and melts in the Earth’s molten mantle.

A diagram showing ocean crust from a heavier tectonic plate bent downward as it enters the Earth's  mantle under the lighter tectonic plate over it.
At a subduction zone, heavier crust is dragged down to the Earth’s mantle where it melts. Areas along a subduction zone often have increased volcanic activity and earthquakes.
Image via Booyabazooka / Wikimedia Commons.

There are several plates causing seismic activity along the Ring of Fire. In most locations, the plates are colliding, causing subduction zones. (An exception: in a section of western North America, the plates are rubbing against each other laterally. This builds up tension that is occasionally released as earthquakes.)

Some of these subduction zones are also the deepest parts of the ocean. The Marianas Trench, 36,037 feet (10,984 m) — that’s 6.8 miles (11 km) — below sea level at its deepest known point, is in a subduction zone.

When tension from a bending plate is released, earthquakes happen. At some locations, molten rock is able to infiltrate through the crust to create volcanoes. Most of these seismic activities happen undersea.

A map of the world's continents with an overlay showing the outlines of major tectonic plates on land and sea.
A map of the world with an overlay of major tectonic plates. In the Ring of Fire, the Pacific Plate is the major central plate, flanked by several major plates and smaller ones. Click this link for a larger view.
Image via USGS / Wikimedia Commons.

Bottom line: The Ring of Fire is a region of active seismic activity caused by interacting tectonic plates. It includes most of Earth’s volcanoes and earthquakes.

A street in Alaska showing a steeply-collapsed section due to a landslide triggered by the earthquake.
Fourth Avenue of Anchorage, Alaska after the March 27, 1964 earthquake. Image via U.S. Army / Wikimedia Commons.
Posted 
June 8, 2021
 in 
Earth

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