Volcanic eruptions

Earth letting out the fire inside it

Earth is very hot inside — 5,000 °C! In some places molten rock (magma) breaks through the crust — that's a volcano. When it erupts, lava flows and ash rises 30 km into the sky. Volcanoes aren't scattered randomly — they line up around the Pacific in the 'Ring of Fire', because that's where Earth's plates collide. See the red dots on the globe? Each one is an active volcano. They're dangerous, but volcanic ash makes soil very fertile.

Volcanoes form at tectonic plate boundaries (subduction — the Ring of Fire, 75% of active volcanoes; rifts — Iceland, East Africa) and at 'hotspots' (Hawaii, Yellowstone). Types: shield (Mauna Loa — runny basalt lava, gentle), stratovolcano (Fuji, Vesuvius — sticky lava, explosive), caldera (supervolcanoes). Eruption power is measured on the VEI scale (0–8): Tambora 1815 (VEI 7) — the 'year without a summer', global temperature fell 0.5 °C; Krakatoa 1883 — heard 4,800 km away; Pinatubo 1991 — its ash cooled the climate for 2 years. There are 1,500 active volcanoes worldwide and 50–70 erupt each year; 800 million people live within 100 km of one. Volcanoes created the atmosphere and oceans; geothermal energy (Iceland — 25%). Central Asia has no active volcanoes — it's far from plate boundaries.

Fun facts

• The 1883 eruption of Krakatoa was heard 4,800 km away — the distance from Tashkent to London!
• Volcanic ash makes soil so fertile that people live nearby despite the danger.
• Uzbekistan has no active volcanoes — we're far from plate boundaries.