We usually associate earthquakes with tectonic plates rubbing together, but that doesn't appear to be what happened Monday.

The Bureau of Reclamation has a project in the Paradox Basin where the epicenter of the quake was located.

The project involves removing salt from groundwater before it enters the river, to improve water quality. The salt brine is then injected deeper into the ground. It is the result of this action that caused the quake on Monday, scientists believe.

The USGS monitors seismic activity in the state and remarked there has been increased seismic activity in Colorado. Not just in the Paradox basin, but in other parts of the state.

The additional activity underground that seems to be man-made comes from wastewater that results from fracking, it is believed.

While the quake on Monday had nothing to do with oil drilling the result was the same. Injecting anything lower parts of the earth can only build up the pressure underground and once that pressure gets too high, we get earthquakes.

There were six aftershocks from Monday's event, none higher than 2.1.