The Hunga Tonga-Hunga Ha’apai volcano which massively erupted lies along the Pacific ‘Ring of fire’, and is just over 60 kilometers from the island nation of Tonga.

What is the Pacific ‘Ring of Fire’?

• The Pacific ‘Ring of Fire’ or Pacific rim, or the Circum-Pacific Belt, is an area along the Pacific Ocean that is characterized by active volcanoes and frequent earthquakes.
• Volcanic arcs and oceanic trenches partly encircling the Pacific Basin form the so-called Ring of Fire.
• It is home to about 75 per cent of the world’s volcanoes – more than 450 volcanoes.
• Also, about 90 per cent of the world’s earthquakes occur here.

Its spread

• Its length is over 40,000 kilometres and traces from New Zealand clockwise in an almost circular arc covering Tonga, Kermadec Islands, Indonesia.
• It is moving up to the Philippines, Japan, and stretching eastward to the Aleutian Islands, then southward along the western coast of North America and South America.

Seismic activity of the region

• The area is along several tectonic plates including the Pacific plate, Philippine Plate, Juan de Fuca plate, Cocos plate, Nazca plate, and North American plate.
• The movement of these plates or tectonic activity makes the area witness abundant earthquakes and tsunamis every year.
• Along much of the Ring, tectonic plates move towards each other creating subduction zones.
• One plate gets pushed down or is subducted by the other plate.
• This is a very slow process – a movement of just one or two inches per year.
• As this subduction happens, rocks melt, become magma and move to Earth’s surface and cause volcanic activity.

What has happened in recent eruption in Tonga?

• In the case of Tonga, the Pacific Plate was pushed down below the Indo-Australian Plate and Tonga plate, causing the molten rock to rise above and form the chain of volcanoes.
• Subduction zones are also where most of the violent earthquakes on the planet occur.
• The December 26, 2004 earthquake occurred along the subduction zone where the Indian Plate was subducted beneath the Burma plate.

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