Read about the seismograph, what it measures, how it works, and how it has helped scientists to better understand earthquakes both in the past and today.
What’s a Seismograph?
Earthquakes are fascinating and frightening at the same time. Have you ever wondered how scientists study these earth-shaking events? They use what’s called a seismograph, also called a seismometer, which is an instrument that measures and records seismic waves that move through the earth as the result of an earthquake.A modern seismograph can help scientists detect earthquakes and measure several aspects of the event:
- The time at which the earthquake occurred
- The epicenter, which is the location on the surface of the earth below which the earthquake occurred
- The depth below the earth’s surface at which the earthquake occurred
- The amount of energy released by the earthquake
Scientists measure and record this data to learn more about earthquakes, tectonic plates, and Earth’s layers.
Earthquakes are difficult to predict, but scientists studying them hope to use seismographic measurements to be able to make more accurate predictions.
How a Seismograph Works
The idea behind a seismograph is fairly simple. A basic seismograph includes a solid base and a heavy weight suspended from a spring over the base. A pen hangs from the weight and a rotating drum with paper sits below it on the base. The tip of the pen touches the drum. When the earth shakes from an earthquake, the drum rotates, and the weighted pen moves back and forth due to the motion of seismic waves.
The pen records the movement on the drum. The paper recording of an earthquake is called a seismogram.
The most high-tech seismographs used by scientists studying earthquakes today are sophisticated and precise. They are based on the same concept as a basic, simple seismograph, but make use of electronics, magnets, and amplifiers in order to accurately and precisely measure the smallest ripples in the earth caused by earthquakes.
- Seismographs: Seismographs are measuring devices used to scale seismic waves caused by earthquakes.
- Seismogram: The paper recording the results and measurements that are taken are called seismograms.
- Richter Scale: The Richter Scale is a popular tool that uses a logarithmic scale to measure seismic wave magnitude.
- Moment Magnitude Scale: Moment magnitude scale is a similar logarithmic measuring scale that applies to a wider range of types and sizes of earthquakes.
Once you’ve reviewed the lesson, you are ready to:
- Define seismograph
- Describe how a seismograph works
- Compare and contrast the Richter Scale and moment magnitude scale
- Recall the first seismograph and who invented it