Volcanoes Facts for Kids
Explosive facts about volcanoes and geology
The 1883 eruption of Krakatoa in Indonesia was so loud it was heard over 3,100 miles away in Australia and the island of Rodrigues near Mauritius. The pressure wave circled the globe multiple times.
There are two main types of lava flow in Hawaii named by their Hawaiian words: pahoehoe (pa-HOY-hoy), which is smooth and ropy, and a'a (AH-ah), which is jagged and sharp. They can even come from the same eruption at the same time.
When lava erupts underwater, the outer surface chills almost instantly in the cold seawater, forming rounded blobs called pillow lava. These pillow shapes are the most common type of lava formation on Earth.
The Hawaiian Islands formed as the Pacific Plate slowly drifted over a fixed 'hotspot' of magma in Earth's mantle. Each island in the chain is older than the one to its southeast, creating a trail of volcanoes pointing toward the hotspot's current position.
Large volcanic eruptions inject sulfur dioxide gas high into the stratosphere, where it forms a haze of tiny droplets that reflect sunlight away from Earth. The 1991 eruption of Mount Pinatubo cooled global temperatures by about 1Β°F for nearly two years.
A lahar is a deadly volcanic mudflow that forms when erupting material mixes with water β from rain, melting snow, or a crater lake. Lahars can travel at 40 mph and bury entire towns, and they remain a danger for years after an eruption ends.
Olympus Mons on Mars is the largest known volcano in the solar system. It stands about 72,000 feet tall β nearly three times the height of Mount Everest β and is so wide it would cover the entire state of Arizona.
Volcanic eruptions are measured on the Volcanic Explosivity Index (VEI), a scale from 0 to 8. The largest eruptions (VEI 8) are called 'supervolcanic' and eject more than 240 cubic miles of material β enough to bury Texas under 10 feet of ash.
Fumaroles are cracks or openings in the Earth's crust near volcanoes that constantly release steam and toxic gases like sulfur dioxide and hydrogen sulfide. Some fumaroles have been active for hundreds of years without a full eruption.
Mount Pinatubo in the Philippines had been dormant for over 600 years before its catastrophic 1991 eruption. It was the second-largest volcanic eruption of the 20th century and ejected so much ash it was detected from space.