Earthquake Magnitude vs. Intensity: The Difference Explained
Magnitude measures earthquake size; intensity describes shaking at a location. Compare the two with a simple example and USGS guidance.
Magnitude describes the earthquake at its source
Magnitude estimates the size of an earthquake. It is not a measurement of the shaking at your address. Different calculation methods and additional observations can produce revised estimates, so an early magnitude in a news headline may change. Check the event’s latest USGS report and the time of that update.
Intensity describes shaking at a place
The same earthquake produces different shaking intensities in different communities. Distance from the source, earthquake depth and local ground conditions affect what people experience. Soft ground can shake differently from nearby bedrock. Two earthquakes with similar magnitudes can therefore produce very different patterns of shaking.
One earthquake, different experiences
Consider an illustrative earthquake recorded at magnitude 5.3. Two towns can experience different shaking from that same event because their distance and ground conditions differ. The earthquake does not have a separate magnitude for each town; the local intensity can differ. This example does not predict how much damage either town would experience.
Does intensity VI mean magnitude 6?
No. Modified Mercalli intensity uses Roman numerals to describe local shaking and effects. Magnitude is a different measurement, usually shown as a number with a decimal. Do not convert VI directly to magnitude 6 or compare them as the same scale. When reading a report, check which measurement the label names.
What a magnitude cannot tell you
A magnitude alone does not confirm damaged buildings, injuries or fatalities. A point on the map locates an event, not its full area of impact. Keep physical measurements separate from impact reports. When a source has not supplied a damage assessment, describe the impact as unconfirmed rather than assuming there was none.
Use the event page as your starting point
Open the linked USGS event page for the latest magnitude, origin time and depth. Where available, review the shaking information alongside those measurements. On StormScapes, the incident timeline and source timestamps help distinguish a revised report from a separate earthquake. For immediate protective action, use official earthquake safety guidance and local instructions.
Official sources
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