Why Japan, Chile and Alaska all shake: a ring of volcanoes and earthquakes round the Pacific.
🌍 Play this lesson on the globe
The red dots are big volcanoes and the yellow dots are big earthquakes. A glowing line joins them into a ring round the Pacific Ocean! Tap a dot to find out more.
The Earth’s skin is cracked into huge slabs called plates. The dotted lines show where the slabs meet. They are drawn simple here, but they run right under the ring of volcanoes and quakes.
Off South America, an ocean plate is pushing into the continent. Drag the slider to shove it underneath. Watch the rock melt deep down — and see what pops up on the globe!
The slabs do not slide smoothly. They get stuck for years, bend, then snap past each other all at once. That snap is an earthquake.
Some slips happen under the sea. The sea floor jumps up and lifts the whole sea above it. The water races out in all directions as a tsunami.
The biggest earthquake ever measured shook this ring in 1960. Plates crashing together can build mountains too — try the Himalayas lesson next!
🌍 Play this lesson on the globe
The globe pictures are simplified to show the idea. Earth images: NASA Blue Marble (public domain).