Magnitude measures the energy released at the source of the earthquake. Magnitude is determined from measurements on seismographs. Intensity measures the strength of shaking produced by the earthquake at a certain location.
Intensity is determined from effects on people, human structures, and the natural environment.
The following gives intensities that are typically observed at locations near the epicenter of earthquakes of different magnitudes. Felt quite noticeably by persons indoors, especially on upper floors of buildings. Many people do not recognize it as an earthquake. Standing motor cars may rock slightly. Vibrations similar to the passing of a truck.