# Scales that Represent Earthquake Magnitude

## Scientists use different scales to indicate the intensity and magnitude of an earthquake including the Mercalli, Richter and moment magnitude.

Estimated3 minsto complete
%
Progress
Practice Scales that Represent Earthquake Magnitude

MEMORY METER
This indicates how strong in your memory this concept is
Progress
Estimated3 minsto complete
%
The Magnitude of Magnitude

### The Magnitude of Magnitude

Credit: Unknown
Source: http://en.wikipedia.org/wiki/File:1755_Lisbon_earthquake.jpg

This engraving shows Lisbon, Portugal in flames and being inundated by tsunami after the November 1, 1755 earthquake. There were no seismographs around, so the magnitude is estimated to have been between 8.5 and 9.0.

#### Why It Matters

• Earthquake magnitude measures the energy it releases.
• Magnitude is measured on an exponential scale: a gain in one whole number is an increase of 33-times the amount of energy released.
• The Richter Magnitude scale measures the amplitude of the largest wave (shaking amplitude). Each whole number increase in shaking amplitude is a factor of 10.
• Credit: U.S. Department of the Interior | U.S. Geological Survey
Source: http://earthquake.usgs.gov/learn/glossary/?termID=149

Richter magnitude scale developed in 1935 to estimate the size of earthquakes [Figure2]

• As scientists refine numbers, a reported earthquake magnitude may change.
• These days, earthquake magnitudes are reported on the Moment Magnitude Scale.

#### Can You Apply It?

1. In the video, the difference from one magnitude to the next is 33-times. Which scale are they using?
2. How much more energy is released by an earthquake that is three whole numbers bigger than another earthquake? Show the math.
3. In the video, on the image with circles for earthquake magnitudes, a 9.5 in Chile is the largest quake. Where is the 5.8 in Virginia on that image? Why?
4. The 1755 Lisbon earthquake is estimated to have been between magnitude 8.5 and 9.0. How many times more energy would be released if it were 9.0 than 3.5?

### Notes/Highlights Having trouble? Report an issue.

Color Highlighted Text Notes

1. [1]^ Credit: Unknown; Source: http://en.wikipedia.org/wiki/File:1755_Lisbon_earthquake.jpg; License: CC BY-NC 3.0
2. [2]^ Credit: U.S. Department of the Interior | U.S. Geological Survey; Source: http://earthquake.usgs.gov/learn/glossary/?termID=149; License: CC BY-NC 3.0

### Explore More

Sign in to explore more, including practice questions and solutions for Measuring Earthquake Magnitude.