The Richter scale does not have an upper limit. The Richter scale is a logarithmic representation of the amount of energy released by an earthquake, or its magnitude. As of 2014, the earthquake that rated highest in recorded history was a 9.5-magnitude quake in Chile in 1960.
Earthquakes that rate at a 7 or above on the Richter scale are considered major. The majority of earthquakes register at 3 or lower.
The Mercalli scale is another rating system for earthquakes that quantifies the damage an earthquake caused. Mercalli scale ratings are rendered in Roman numerals, up to XII. The Mercalli scale is determined subjectively from observations, rather than measured scientifically like the Richter scale.