A key part of that for the linemen is that they are impacting each other on nearly every play, though maybe not with same magnitude [of impact] as wide receivers. (scientificamerican.com)
But between 2009 and 2013 that number rose nearly 100 earthquakes per year of the same magnitude. (businessinsider.com)
Geologists said before 2009, the state historically averaged 1.5 earthquakes of magnitude - 3 or greater each year, and is now experiencing 2.5 earthquakes of the same magnitudes each day. (businessinsider.com)