The Ring of Fire is a zone of frequent earthquakes and volcanic eruptions that encircles the basin of the Pacific Ocean. It is associated with a nearly continuous series of oceanic trenches, island arcs, and volcanic mountain ranges and / or plate movements. It is sometimes called the circum-Pacific seismic belt.

About 81% of the world's largest earthquakes occur within the Ring of Fire. [1] The Alpide belt, which extends from Java to Sumatra through the Himalayas, the Mediterranean, and out into the Atlantic, accounts for another 17%, and the Mid-Atlantic Ridge is a third prominent earthquake belt.

The Ring of Fire is a direct consequence of plate tectonics and the movement and collisions of crustal plates [2]. The eastern section of the ring is the result of the Nazca Plate and the Cocos Plate being subducted beneath the westward moving South American Plate. A portion of the Pacific Plate along with the small Juan de Fuca Plate are being subducted beneath the North American Plate. Along the northern portion the northwestward moving Pacific plate is being subducted beneath the Aleutian Islands arc. Further west the Pacific plate is being subducted along the Kamchatka - Kurile Islands arcs on south past Japan. The southern portion is more complex with a number of smaller tectonic plates in collision with the Pacific plate from the Mariana Islands, the Philippines, Bouganville, Tonga, and New Zealand. Indonesia lies between the Ring of Fire along the northeastern islands adjacent to and including New Guinea and the Alpide belt along the south and west from Sumatra, Java, Bali, Flores, and Timor. The December 2004 earthquake just off the coast of Sumatra was actually a part of the Alpide belt. The famous and active San Andreas Fault zone of California is a transform fault which offsets a portion of the East Pacific Rise under southwestern United States and Mexico.

A number of land and sea features are in the Ring of Fire: (here listed clockwise)

• New Zealand
• Kermadec Trench
• Tonga Trench
• Bougainville Trench
• Indonesia
• Philippines
• Philippine Trench
• Mariana Trench
• Izu Bonin Trench
• Ryukyu Trench
• Japan
• Japan Trench
• Kurile Trench
• Kamchatka
• Aleutian Islands
• Aleutian Trench
• Alaska
• Cascade Range
• California
• Mexico
• Middle America Trench
• Guatemala
• Colombia
• Ecuador
• Peru
• Peru-Chile Trench

Reference

• Historic Earthquakes & Earthquake Statistics - USGS
• "Ring of Fire", Plate Tectonics, Sea-Floor Spreading, Subduction Zones, "Hot Spots" - USGS
• Map of the Ring of Fire