Most geologically active region on Earth

The most geologically active region on Earth is the “Ring of Fire”, a highly volatile seismic zone that surrounds most of the Pacific Ocean. It is responsible for around 90% of all earthquakes and some 75% of all volcanic eruptions; indeed, most of our planet’s 1,500-plus active volcanoes are located within the region. Geological activity along this 40,000-km-long (24,850-mile) tectonic belt affects a number of countries, including many in South America, as well as the USA and Canada, China, Japan, Indonesia, the Philippines, Australia and New Zealand.

The reason that this particular zone is so volatile is that several of Earth’s tectonic plates meet and interact along the “Ring of Fire”. When they slide past each other, the action increases and releases tension in the Earth’s crust, giving rise to earthquakes of varying strengths. When tectonic plates overlap at boundaries known as “subduction zones”, one plate is pushed down by the other and its rock melts to form magma, creating prime conditions for both seismic and volcanic activity.

The Ring of Fire has borne witness to some of the superlative seismic events in modern history, including the largest eruption by volume on record: Tambora, on the Indonesian island of Sumbawa, which ejected some 150–180 km3 (36–43 cubic miles) of material on 5–10 April 1815. The fallout entailed a drop in the global average temperatures by as much as 3°C (5.4°F), and led to 1816 being dubbed “the year without summer”, with massive crop failures and other weather-related disruptions throughout Europe and North America owing to the sun-blocking dust and ash from Tambora suspended in the atmosphere.

The next most earthquake-prone region on Earth is the Alpide Belt, responsible for 5–6% of all tremors and some 17% of the severest ones. This seismic zone stretches for more than 15,000 km (9,300 miles) from the Atlantic Ocean eastward across Europe and Asia to the East Indies.