Stratovolcano

volcanoes · geology · explosive

Layers upon layers. Stratovolcanoes are built up like a stack of pancakes, with alternating layers of hardened lava and rock called tephra. Each eruption adds new layers on top, making them taller and steeper over time.

Explosive power. Unlike other volcanoes that ooze lava gently, stratovolcanoes erupt with a bang. Their thick, sticky magma gets trapped and builds up pressure underground until it finally explodes outward.

Sticky lava stops fast. The lava from stratovolcanoes is so thick and gooey that it cools and hardens quickly, usually before it spreads very far. Sometimes it flows up to 8 kilometers, but it doesn't travel as far as lava from other volcano types.

Summit craters collapse. Some stratovolcanoes develop giant collapsed craters at their peak called calderas. These form when the volcano empties out and the ground caves in like a sinkhole.

Made of silica-rich stuff. The magma that feeds stratovolcanoes is packed with silica, which makes it thick and sticky. This is why these volcanoes build steep cones instead of spreading out flat like shield volcanoes.