## TL;DR

Volcanoes are openings where magma, ash, and gases escape from Earth's interior. Types: shield (gentle slopes, Hawaii, Mauna Loa — largest volcano on Earth), stratovolcano (steep, explosive, Mount Fuji, Vesuvius), cinder cone (smallest). Ring of Fire: Pacific Ocean boundary with 75% of world's active volcanoes.

## Core Explanation

VEI (Volcanic Explosivity Index): 0-8 logarithmic scale. Mount Tambora (1815, VEI 7): 'year without a summer,' global crop failures. Krakatoa (1883): heard 4,800 km away, caused tsunamis. Mount St. Helens (1980): lateral blast, entire side of mountain collapsed. Supervolcanoes: Yellowstone (VEI 8 potential). Benefits: volcanic soil is extremely fertile, geothermal energy.

## Further Reading

- [Volcanoes: Global Perspectives (Lockwood, Hazlett, de la Cruz-Reyna, 2nd Ed)](https://www.wiley.com/en-us/Volcanoes%3A+Global+Perspectives%2C+2nd+Edition-p-9781119477532)