Earthquake magnitude and intensity are always correlated. True or False?

• A. True
• B. False
• C. Sometimes
• D. Always

Answer: (B)

Shaking intensity at a location varies independently from the overall energy released by the earthquake. Magnitude is a single value that describes how much energy the fault released during the event, while intensity measures how strongly ground shaking is felt at a specific place and can be influenced by distance from the rupture, depth, the materials underfoot (softer soils vs solid bedrock), and the way seismic waves travel through the crust.

Because of those factors, a large, powerful earthquake can produce only modest shaking at a distant site or over hard rock, while a smaller quake happening right next to soft sediments or a basin can cause very strong, damaging shaking locally. That variability is why magnitude and intensity aren’t always in lockstep, so the statement is false.