I wonder if the geologist studying the recent local earthquakes in Youngstown had taken into account the nearby loading of the landfill that lies just about a mile to the north of the injection well.
It has been documented many times that the building of large dams (loading) cause earthquakes in the order of 2 to 3 or more on the Richter scale soon after the dams begin to fill. This occurred near dams that had no former records of quakes.
There also have been quakes where large amounts of coal have been removed form underground (unloading).
Water weighs 62 pounds per cubic foot so the water in a newly large lake would add a downward pressure of billions of pounds. The local landfill probably weighs two to three times the weight of water per cubic foot and may not be as noticeable as a large lake and therefore overlooked and not factored in.
It may be that the injection well lubricated and triggered small quakes that relieved the pressure and stress that the landfill caused. Without this lubrication we may have had a quake of 6 or more on the Richter scale.
Geologist should try a 12-inch pipe set vertical in the center of a purposed future landfill or dam and the bottom of the pipe set in bedrock. In this way using lasers or other means we could measure the downward movement of the rock layer, giving geologist information that could be used elsewhere, say in the building of large skyscrapers.
-- Don Miller, Girard