The Ring of Fire

the Pacific Ring of Fire (or sometimes just the Ring of Fire) 

is an area where large numbers of 

earthquakes and volcanic eruptions occur 

in the basin of a Pacific Ocean. In a 40,000 km horseshoe shape, 

it is associated with a nearly continuous 

series of oceanic trenches, volcanic arcs, and volcanic belts or 

plate movements. The Ring of Fire has 452 volcanoes and 

is home to over 75% of the world's active and dormant 

volcanoes.[1] It is sometimes called the 

circum-Pacific belt or the circum-Pacific seismic belt.

Eruption of Mount St. Helens on July 22, 1980.About 90% of the world's 

earthquakes and 80% of the world's largest earthquakes occur 

along the Ring of Fire. The next most seismic 

region (5–6% of earthquakes and 17% of the 

world's largest earthquakes) is the Alpide belt, 

which extends from Java to Sumatra through the Himalayas, 

the Mediterranean, and out into the Atlantic. 

The Mid-Atlantic Ridge is the third most prominent 

earthquake belt. 

The Ring of Fire is a direct result of plate tectonics and the 

movement and collisions of crustal plates.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.The Cocos 

Plate is being subducted beneath the Caribbean Plate, 

in Central America. 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 Peninsula 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, Bougainville, 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 famous and very 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. 

The motion of the fault generates numerous small earthquakes, 

at multiple times a day, most of which are too small to be felt.

The active Queen Charlotte Fault on the west coast of the 

Queen Charlotte Islands, British Columbia, Canada, has generated three 

large earthquakes during the 20th century: a magnitude  event in 1929, 

a magnitude 8.1 occurred in 1949 (Canada's largest recorded earthquake) 

and a magnitude 7.4 in 1970.

credits : http://en.wikipedia.org