Volcanoes Active

Approximately 1,500 volcanoes are potentially active worldwide; about 50 erupt each year. They form at tectonic plate boundaries (subduction zones produce stratovolcanoes; spreading ridges produce shield volcanoes) and hotspots (Hawaii, Yellowstone). The 'Ring of Fire' — encircling the Pacific Ocean — contains 75% of the world's active volcanoes and produces 90% of the world's earthquakes. Kilauea (Hawaii) is the world's most continuously active volcano — erupting nearly continuously since 1983. Etna (Sicily) has been active for 3,500+ years of recorded history. Vesuvius (Italy) is most famous for destroying Pompeii in 79 CE — it is now surrounded by 3 million people in one of the world's most dangerous volcanic zones. Krakatoa's 1883 eruption lowered global temperatures 1.2°C, turned sunsets red worldwide, and killed 36,000 people in tsunamis.