Why are large earthquake's less common far away from plate boundaries?

The mantle convection causes an upward push and downward pulling that may heavily contribute to where earthquakes further from plate lines are found. In his study, Becker suggests that earthquakes away from plate boundaries may happen because of movement occurring beneath plates

Answer: Over 90% of earthquakes - including almost all of the largest and most destructive ones - happen at or near so-called plate boundaries, where the 15 or so major subdivisions ("plates") of the Earth's crust and uppermost mantle move towards, alongside, or away from each other