The Pacific ‘Ring of Fire’, a significant geological formation known for its active volcanoes and frequent earthquakes, has recently been in news due to the eruption of the Hunga Tonga-Hunga Ha’apai volcano just over 60 kilometers from the island nation of Tonga. This article aims to provide an in-depth look at the key features and causes of these frequent seismic activities.
About the Pacific ‘Ring of Fire’
Fundamentally known as the Pacific rim or the Circum-Pacific Belt, the ‘Ring of Fire’ is an area along the Pacific Ocean characterized by a concentration of active volcanoes and earthquake occurrences. It houses about 75% of the world’s volcanoes – more than 450 of them – and is the site for about 90% of the world’s earthquakes.
Geographical Stretch of the Ring
The ‘Ring of Fire’ is stretched over approximately 40,000 kilometers, tracing boundaries between several tectonic plates including the Pacific, Juan de Fuca, Cocos, Indian-Australian, Nazca, North American, and Philippine Plates. It traverses the western coast of South and North America, crosses the Aleutian Islands in Alaska, runs down the eastern coast of Asia past New Zealand, and reaches the northern coast of Antarctica. Countries spanning this vast ring include Bolivia, Chile, Ecuador, Peru, Costa Rica, Guatemala, Mexico, the United States, Canada, Russia, Japan, the Philippines, Australia, Papua New Guinea, Indonesia, New Zealand, and Antarctica.
Causes of Volcanic Activity
A key factor causing volcanic activity is the movement of tectonic plates towards each other, creating what’s known as subduction zones. In such zones, one plate gets pushed down or is subducted by the other. This extremely slow process, with a movement rate of just one or two inches per year, results in rocks melting and turning into magma that rises to the Earth’s surface, causing volcanic activities. For instance, Tonga’s recent volcanic activity originated from the subduction of the Pacific Plate below the Indo-Australian Plate and the Tonga plate.
Recent Research on Tectonic Activities
Recent studies suggest that the Pacific Plate, a key driver of tectonic activities in the Ring of Fire, is cooling off. The youngest parts of the Pacific Plate (about 2 million years old) are contracting at a faster rate than the older parts of the plate (about 100 million years old). These young, more active areas are located in the northern and western parts of the plate, within the Ring of Fire.
Understanding Subduction
Subduction is the phenomena where tectonic plates shift and one plate is shoved under another. This displacement of the ocean floor leads to what experts refer to as ‘mineral transmutation’, which eventually results in the formation of volcanoes. More specifically, when a ‘downgoing’ oceanic plate is forced into a hotter mantle plate, it heats up triggering a reaction of volatile elements that produce magma. Consequently, the magma rises through the overlying plate and spurts out onto the surface. In essence, a subduction zone can be likened to the biggest crash scene on Earth – a point of collision between two tectonic plates. Here, one plate bends and slides underneath the other, curving down into the mantle, the layer beneath the crust.
