Measuring Earthquake Strength
Know that scientists measure earthquakes using seismometers, that earthquakes release energy that travels as waves through the ground, and that a magnitude scale describes their strength
What a learner can do afterwards
- Explain that a seismometer is an instrument that detects and records ground shaking
- Describe earthquake energy as waves that travel outward from where rocks broke
- Interpret a magnitude number as a measure of an earthquake's strength
The lesson
When rocks break along a fault, they release a burst of energy. Scientists catch that shaking with a tool called a seismometer. It sits on the ground and records every wiggle, even shaking too small for you to feel.
That energy does not stay in one place. It spreads out as waves that travel through the ground, moving away from the spot where the rocks broke. The waves get weaker the farther they travel.
A news report says an earthquake was magnitude 3. People nearby might feel a light shake and hear dishes rattle. Another report says magnitude 7. That earthquake can crack roads and knock down buildings. The bigger number tells you it was the stronger earthquake.
When you hear a magnitude number on the news, remember it is telling you how strong that earthquake was. The seismometer recorded the shaking, and scientists turned it into that single number.
A seismometer records shaking energy that spreads out as waves, and the magnitude number tells you how strong the earthquake was.
Watch it
Where it sits
Learn first
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.