Earthquake Intensity: What controls the shaking you feel during an earthquake?

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Loma Prieta Seminary Earthquake Damage

ERN Item Type: 

  • Classroom Activities


Incorporated Research Institutions for Seismology (IRIS)


We compare a light bulb to an earthquake to clarify the difference between magnitude and intensity, two concepts that are often used interchangably, but in error. Though both are related to a measured earthquake, intensity reflects what is felt during an earthquake at many locations, and the magnitude is a single measured value. Intensity was originally calculated by gathering personal, anecdotal reports during an earthquake, but the definitive intensity is assigned either via Did You Feel It (DYFI), or via expert judgement, as was done historically. This resource included animations and lessons on earthquake intensity.

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