The Pacific Ring of Fire

The Pacific Ring of Fire is an area where large numbers of earthquakes andvolcanic eruptions occur in the basin of the Pacific Ocean. In a 40,000 kmhorseshoe shape, it is associated with a nearly continuous series of oceanictrenches, volcanic arcs, and volcanic belts and/or plate movements. The Ring ofFire has 452 volcanoes and is home to over 75% of the world's active and dormantvolcanoes. It is sometimes called the circum-Pacific belt or the circum-Pacificseismic belt. 90% of the world's earthquakes and 80% of the world's largestearthquakes occur along the Ring of Fire. The next most seismic region (5–6% ofearthquakes and 17% of the world's largest earthquakes) is the Alpide belt,which extends from Java to Sumatra through the Himalayas, the Mediterranean, andout into the Atlantic. The Mid-Atlantic Ridge is the third most prominentearthquake belt.[1][2]The Ring of Fire is a direct result and consequence of plate tectonics and themovement and collisions of crustal plates.[3] The eastern section of the ring isthe result of the Nazca Plate and the Cocos Plate being subducted beneath thewestward moving South American Plate. A portion of the Pacific Plate along withthe small Juan de Fuca Plate are being subducted beneath the North AmericanPlate. Along the northern portion the northwestward moving Pacific plate isbeing subducted beneath the Aleutian Islands arc. Further west the Pacific plateis being subducted along the Kamchatka Peninsula arcs on south past Japan. Thesouthern portion is more complex with a number of smaller tectonic plates incollision with the Pacific plate from the Mariana Islands, the Philippines,Bougainville, Tonga, and New Zealand. Indonesia lies between the Ring of Firealong the northeastern islands adjacent to and including New Guinea and theAlpide belt along the south and west from Sumatra, Java, Bali, Flores, andTimor. The famous and very active San Andreas Fault zone of California is atransform fault which offsets a portion of the East Pacific Rise undersouthwestern United States and Mexico. The motion of the fault generatesnumerous small earthquakes, at multiple times a day, most of which are too smallto be felt.[4][5] The active Queen Charlotte Fault on the west coast of theQueen Charlotte Islands, British Columbia, Canada, has generated three largeearthquakes during the 20th century: a magnitude 7 event in 1929, a magnitude8.1 occurred in 1949 (Canada's largest recorded earthquake) and a magnitude 7.4in 1970.[6]The December 2004 earthquake just off the coast of Sumatra was actually a partof the Alpide belt.[citation needed]