Interactive Explainer
What causes earthquakes?
Most earthquakes happen when tectonic forces keep pushing on rocks along a fault until the rocks can no longer hold. Then the fault slips suddenly, stored elastic energy is released, and seismic waves race outward through the ground.
Earthquakes are sudden releases of built-up stress, usually along faults at plate boundaries or other stressed cracks in the crust.
If a fault is stuck by friction, stress can keep building for years or centuries before a slip finally happens.
Shallow earthquakes often shake the surface more intensely near the rupture than deeper ones of similar size.
Try It Yourself
Earthquake Lab
Load a fault with more stress, change how sticky it is, move the rupture deeper, or step farther from the epicenter to see how the shaking picture changes.
What changes the fastest
What is driving the result
The Big Idea
What is actually happening?
An interactive explainer about how stress builds along faults, why rocks suddenly slip, and how depth and distance change the shaking you feel.
Plate motion or local crustal motion loads the rock
Tectonic plates keep moving even when faults do not slip smoothly, so stress can build up in the surrounding rocks.
Friction holds the fault for a while
Many faults remain locked because the rough rock surfaces resist sliding, even while the stress keeps increasing.
The fault suddenly breaks free
When the stress overcomes the fault’s strength, the rocks slip. That sudden motion releases energy into seismic waves.
Shaking depends on depth and distance too
A rupture right under you feels different from one far away or deeper underground, even if the total energy release is large.
Good Follow-Up Questions
The details are where this gets interesting
The short answer helps, but the edge cases and comparisons are what make the topic memorable.
The epicenter is not the whole rupture
The epicenter is only the point on the surface above where rupture began. The actual fault break can extend for many kilometers.
Aftershocks are normal
After the main slip, surrounding rock is still adjusting to a new stress pattern. Smaller quakes can follow as the crust rebalances.
Magnitude and intensity are not the same
Magnitude measures the quake’s overall size. Intensity describes how strongly it is felt in a particular place.
Compare Scenes
Why one earthquake feels sharp and violent while another feels weaker or more rolling
The fault type, depth, and your distance from the rupture all affect the experience.
Fast Answers
Questions people usually ask next
Good science pages should answer the obvious follow-ups without making the reader hunt for them.