Earthquake vs. Tsunami: What's the Difference?
They're closely linked — one frequently causes the other — but they're different events. An earthquake is the shaking of the ground when rock suddenly slips deep within the Earth. A tsunami is a series of huge ocean waves, often triggered when an undersea earthquake abruptly shifts the sea floor. So an earthquake is ground movement; a tsunami is the water it can set in motion.
See the difference, explained visually.
Watch a 2-minute animated lesson comparing earthquake and tsunami.
At a glance
| Earthquake | Tsunami | |
|---|---|---|
| What it is | Shaking of the ground | Giant ocean waves |
| Where | On land or under the sea | In the ocean, hitting coasts |
| Cause | Tectonic plates slipping | Often an undersea earthquake |
| Relationship | Can be the trigger | Can be the result |
| Main danger | Collapsing buildings, shaking | Flooding, walls of water at the coast |
Which should you use?
Earthquake
It's an earthquake when the ground itself shakes from rock movement — felt as trembling, regardless of any water.
Tsunami
It's a tsunami when that disturbance displaces ocean water into a series of huge, fast waves that flood the coast.
Frequently asked questions
- Does every earthquake cause a tsunami?
- No. Only large earthquakes that abruptly move the sea floor (usually undersea ones) generate tsunamis. Most earthquakes — especially on land — cause no tsunami at all.
- Can a tsunami happen without an earthquake?
- Yes, though less commonly. Underwater landslides, volcanic eruptions, and rarely meteorite impacts can also displace enough water to cause a tsunami.
- Which is more dangerous?
- Both can be deadly. Earthquakes threaten with collapsing structures; tsunamis with sudden, far-reaching flooding. A large undersea earthquake can bring both at once.