The Ring of Fire is named for the long circle of volcanoes and seismically unstable plates and faults which compose it. The ring runs along the Pacific Ocean and is the site of approximately 90 percent of the world's seismic activity and 75 percent of all active volcanic activity.
The Ring of Fire incorporates 452 volcanoes. It is arranged in a rough horseshoe shape, belying its name, stretches 25,000 miles from end to end. Volcanoes, both dormant and active, stretch through Antarctica, New Zealand, Japan and many other locations to form a very rough circle.
The Ring of Fire is a site of frequent tectonic activity. Many tectonic plates meet along the ring and shift frequently due to natural tectonic movements and due to building pressure from molten stone welling up from under the earth's crust. This is the cause of many of the earthquakes and seismic events which plague the countries along and surrounding the ring.
Hot spots, or places beneath the earth where temperatures and pressure cause rock to melt, dot the Ring of Fire from end to end. This is what resulted in the many volcanoes that compose the ring and it encourages their continued activity and even the expansion of the ring over geological timescales.