Where the Ground Shakes
Why do earthquakes and volcanoes happen in the same places, over and over?
Your mission: plot real earthquakes on the map and see whether they cluster along the plate boundary lines you learned about in Mission 1, or scatter randomly everywhere.
Earthquakes and volcanoes aren’t scattered randomly around the world — most of them happen in narrow bands that trace out the edges of Earth’s plates. The background map already has the real plate boundaries drawn on it (red = spreading ridge, orange = transform, thick dark-blue line = subduction zone). Switch on the earthquakes and see the pattern for yourself.
What makes an earthquake “notable” here?
Earthquakes happen somewhere on Earth almost every day — most far too small to feel. The dots on this map are only the big ones: magnitude 7.5 or higher, going back to 1970 — real events recorded by scientists, not made-up data. That’s why there are only a couple of hundred dots, not thousands.
(Magnitude is the scale scientists use for how strong an earthquake is. It jumps fast: each whole number up is about 32 times more energy, so a magnitude 8 earthquake releases roughly 32× what a magnitude 7 does.)
What do you notice?
Look at where the dots cluster. Do they scatter evenly across the continents and oceans, or do they hug the coloured boundary lines? Are there more dots — and bigger ones — near the dark-blue subduction lines, or the red ridge lines?
This is one of the strongest pieces of evidence for plate tectonics: earthquakes and volcanoes happen where plates push into each other, pull apart, or grind past one another — not randomly. Subduction zones (where one plate dives beneath another) produce the biggest and deepest earthquakes of all, which is exactly why the “Ring of Fire” around the Pacific is both a subduction-zone map and an earthquake map.
Try it yourself
- Zoom in (with your browser’s zoom) on the “Ring of Fire” around the Pacific Ocean — how many quakes can you count hugging the dark-blue subduction line, compared to the red ridge line?
- Hover or tap a dot to see exactly where and when that earthquake happened.
- Find the biggest dot on the whole map — where was it, and roughly how many times more energy did it release than the smallest dots here?