There isn't a specific classification scale used to describe the depth of origin of earthquakes. Instead, earthquakes are categorized by their depth using a simple numerical scale in kilometers.

Here's how the depth is typically categorized:

* Shallow focus earthquakes: 0-70 km deep

* Intermediate focus earthquakes: 70-300 km deep

* Deep focus earthquakes: 300-700 km deep

These depth classifications are helpful because they correlate with different tectonic processes and often lead to differing earthquake characteristics, such as magnitude and intensity.

Here's a breakdown:

* Shallow focus earthquakes are the most common and generally associated with transform faults and convergent plate boundaries. They are responsible for the majority of earthquake damage.

* Intermediate focus earthquakes are associated with subduction zones, where one tectonic plate slides beneath another. They often cause powerful earthquakes and are less frequent than shallow focus earthquakes.

* Deep focus earthquakes occur within the subducting slab at significant depths. These earthquakes are often very powerful, but their effects on the surface are less pronounced due to their depth.

It's important to note that there are instances where earthquakes can occur outside of these depth ranges, but they are less common.