WHAT IS IT? -- The Ring of Fire is a band of volcanoes and fault lines circling the edges of the Pacific Ocean.

-- Also called the circum-Pacific seismic belt, it is shaped like a horseshoe and is 40,000 km (25,000 miles) long.

-- It runs from Chile, northwards along the South American coast through Central America, Mexico, the west coast of the United States and the southern part of Alaska, through the Aleutian Islands to Japan, the Philippines and Indonesia before curving back toward New Guinea, the southwest Pacific islands and New Zealand.

-- The area's seismic activity results from collisions between tectonic plates.

KEY FIGURES:

-- Of the world's some 1,500 active volcanos, almost 90 percent are in the Ring of Fire, and 75 percent of the Earth's active and dormant volcanoes are located in the area.

-- Ninety percent of the world's earthquakes and 81 percent of the world's largest earthquakes occur within it.

GLOBAL CONTEXT:

-- The next most seismic region (5-6 percent of earthquakes and 17 percent of the world's largest earthquakes) is the Alpide belt, which extends from the Indonesian islands of Java and Sumatra to the Himalayas, the Mediterranean, and out into the Atlantic. This was the plate involved in Sumatra's December 2004 earthquake and resulting tsunami.

-- The Mid-Atlantic Ridge is the third most prominent earthquake belt.

RECENT ACTIVITY:

-- June 12, 2006 - Japanese vulcanologists warn of more eruptions at Mount Sakurajima, on the southern island of Kyushu about 950 km (600 miles) southwest of Tokyo, after it spews volcanic gases 2,000 metres (6,600 ft) into the air.

-- June 12 - A moderate earthquake strikes off the western coast of Indonesia's Sumatra island.

-- June 10 - An explosion from the 1,500-metre (5,000-ft) summit of Bulusan volcano in the Philippines sends ash and steam 1,000 metres (3,300 ft) into the air and showers ash on surrounding villages.

-- May 27 - A 6.3 magnitude earthquake hits Java, killing more than 5,700.

FAMOUS RING OF FIRE ERUPTIONS IN 20TH CENTURY:

-- June 9, 1991 - Mount Pinatubo, 80 km (50 miles) north of Manila, has one of the 20th century's three largest eruptions. More than 700 are killed and 200,000 buildings are destroyed.

-- May 18, 1980 - Mount St. Helens in southwest Washington state erupts, killing 57. The eruption was triggered by a 5.1 magnitude earthquake.