🌋 Volcanoes

A volcano is an opening in Earth's surface where melted rock, gas, and ash from deep underground can escape up to the surface. Most of the time a volcano sits quietly, sometimes for hundreds of years, without anything happening at all. When pressure builds up enough underneath it, the volcano can erupt, sending melted rock and ash out into the open air.

Deep underground, it is hot enough to melt solid rock into a thick, flowing liquid called magma, which is lighter than the solid rock around it and slowly rises upward looking for a way out. As magma rises, gas trapped inside it starts to bubble out, building up pressure the same way shaking a bottle of soda builds up pressure inside. When that pressure finally becomes too much for the rock above to hold back, it bursts through as an eruption, sending magma, now called lava, gas, and ash up and out.

Lava and magma are actually the exact same melted rock, just with different names depending on where it is: magma while it is still underground, and lava once it reaches the surface and flows out into the open air. Lava can be so hot that it glows bright orange or red, and it slowly cools and hardens into solid rock once it is exposed to the air. Depending on how thick or runny the lava is, it can either flow quickly like a river or barely creep along at all.

Volcanoes can be powerful, so people who study them, called volcanologists, keep a close eye on the ones most likely to erupt, watching for small earthquakes, gas leaks, or slight bulges in the ground that often happen just before an eruption starts. Thanks to this careful watching, scientists can often warn people well ahead of time, giving nearby towns a chance to prepare safely. Most volcanoes on Earth are actually quiet and considered safe to live near, and only a small number are watched closely because they show real signs of waking up.