The instrument used to measure and record an earthquake and how long it lasted. Phone apps today allow you to carry your own seismograph in your pocket!
A seismograph Richter scale A seismography phone app
The original scale used to measure the magnitude (strength) of an earthquake was the Richter scale. This scale goes from 1 to 8. Each one-unit increase means that the earthquake is ten times more powerful than it was at the previous unit. It may be unreliable for larger earthquakes.
Moment magnitude scale
The moment magnitude scale (MMS) is used to measure the magnitude of earthquakes. It has replaced the Richter scale because it is more reliable for larger earthquakes. The scale goes from 1 to 10.
Epicentre
1. Examine this diagram and explain each of the key words labelled.
2. Draw and label a diagram explaining what a tsunami is.
3. Name the piece of equipment used to measure an earthquake.
Focus Seismic waves
4. Explain the difference between the Richter scale and the moment magnitude scale.
Using a smart device, investigate seismograph apps that you could download for free. Then try using your device as a seismograph to record any tremors in your classroom or home. If your seismograph picks up any larger tremors, try to investigate why.
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Fun Fact!
The 1960 Chile earthquake was measured an 8.5 on the Richter scale. Scientists revised this using the moment magnitude scale, and the size was re-recorded as magnitude 9.5. This is the largest earthquake ever recorded since seismographs were invented.
