An earthquake is the general term for ground-shaking caused by movement in the Earth's crust, whether mild or devastating. A tremor is often used for a milder shake, or for shaking of the body, such as a tremor in someone's hand. Think of tremor as the smaller, gentler word: every big earthquake could be called a tremor in its early moments, but not every tremor grows into a destructive earthquake.
The core difference
Earthquake covers ground-shaking of any size, while tremor usually points to a mild shake or to trembling in the body.
- earthquake — a sudden shaking of the ground caused by movement in the Earth's crust: Scientists monitor fault lines to predict future earthquakes.
- tremor — a mild earthquake, or the shaking it causes: Residents felt a small tremor early this morning.
- tremor — also an involuntary shaking of the body: A tremor in his hand made it hard to hold the cup steady.
How to tell them apart
News reports often reach for tremor when a quake is too small to cause damage, and switch to earthquake once the shaking is strong enough to matter. A useful memory hook: a tremor trembles, an earthquake quakes — the milder word shares its root idea with trembling hands, while earthquake is built from earth plus quake, a much bigger word for a much bigger event.
Tremor also does double duty outside geology, describing a shake in a voice or a hand, which earthquake never does. If the word is describing a person's body rather than the ground, tremor is the only one of the two that fits.
