All earthquakes don’t shake the Earth the same. People can feel different shaking intensities at different locations. Some earthquakes shake everything (high intensity), and others are not felt at all (low intensity). It is important to compare these earthquakes so we can determine how to prevent damage.

Before seismographs were invented different methods of recording an earthquake were used. In Italy, Giuseppe Mercalli created a 12 point scale in 1902 which was based on stories of damage from people.

Today, the Modified Mercalli Scale represents the local effect or damage caused by an earthquake. The "intensity" reported at different points generally decreases away from the earthquake epicenter. The intensity ranges, from I -XII, is always expressed in Roman numerals. For example, an earthquake of intensity "II" would be barely felt by people, while heavy damage would be assigned a "X."