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Volcanoes and the Ring of Fire
Trace a line around the edge of the Pacific and you have drawn most of the planet's fury: the smoking cones of the Andes, the Cascades above Seattle, the Aleutians, Kamchatka, Japan, the Philippines, Indonesia, and down to New Zealand. It is not a run of bad luck strung around one ocean. It is a seam, the place where the Pacific floor is diving under everything around it.
What the Ring of Fire is
The Ring of Fire is a horseshoe-shaped belt roughly 40,000 kilometres long that traces the rim of the Pacific. It holds about three quarters of the world's active volcanoes and is where roughly ninety percent of the world's earthquakes happen. The engine underneath is subduction: dense slabs of ocean floor sliding beneath the lighter plates around them, melting as they sink and sending magma back up to the surface.
Volcanoes away from the ring
Not every volcano sits on a plate boundary. Some rise over hotspots, plumes of heat pushing up through the middle of a plate, building island chains as the plate drifts slowly overhead. Hawaii is the classic example. Iceland is doubly volcanic, sitting on the Mid-Atlantic Ridge where two plates pull apart. So a volcano is not always a Pacific clue, but far more often than not, it is.
The islands that fire builds
A great many islands are simply volcanoes that broke the surface of the sea. Indonesia, sitting squarely on the ring, has more active volcanoes than any other country. Japan, the Philippines, and the long Pacific island arcs all owe their existence to the same grinding process. Volcanic soil is famously fertile, which is why people crowd onto the slopes generation after generation, risk and all.
Reading a volcano in a clue
A volcano, an earthquake, or a note that a place is "geologically active" tilts the odds toward a plate boundary, and most often toward the Pacific rim. Add a hemisphere or a nearby ocean and the ring does much of the work for you. A lone volcanic island sitting far out in mid-ocean, on the other hand, quietly points to a hotspot instead.
Bottom Line
The Ring of Fire is the belt of volcanoes and earthquakes around the Pacific, born where ocean plates dive beneath their neighbours. It concentrates most of the world's eruptions in one loop, with Indonesia the most volcanic country on it. When a clue smells of smoke, look to a plate boundary first, and to the Pacific rim before anywhere else.
Frequently Asked Questions
What is the Ring of Fire?
The Ring of Fire is a horseshoe-shaped belt around the Pacific Ocean where most of the world's volcanoes and earthquakes occur. It forms where oceanic plates dive beneath neighbouring plates, a process called subduction.
What percentage of volcanoes are in the Ring of Fire?
The Ring of Fire contains roughly 75 percent of the world's active volcanoes and is where about 90 percent of the world's earthquakes happen.
Why do volcanoes form where they do?
Most volcanoes form at the boundaries between tectonic plates, especially where one plate slides beneath another. Others form over hotspots, plumes of heat rising through the middle of a plate, as at Hawaii.
Which country has the most active volcanoes?
Indonesia has more active volcanoes than any other country, because it sits directly on the Ring of Fire where several plates meet.