Three distinct methods to measure earthquakes. Two based on energy and one based on intensity.
- Richter Magnitude Scale: originally developed for southern California. Log scale, which has no upper bound. Small earthquakes may yield negative values. Tends to be inaccurate at >7 magnitudes.
- Moment Magnitude Scale: measurement of the amount of work done during the earthquake. Based on rock strength, area of rupture, and displacement during event.
- Modified Mercalli Intensity Scale: based on the damage associated with a particular event at a particular location. Ranges from I (less damage) to XII (more damage).
