This article talks of Peak Ground Acceleration (PGA)
The greater the PGA, the greater objects will accelerate horizontally thusly experiencing a greater force.
Quote: This map specifically displays the seismic event PGA of a 10-in-100 (10%) chance of exceedence in a 50-year time period. PGA is generally used in the evaluation of building codes, using the Modified Mercalli Intensity Scale (I-X) PGA can be correlated to potential damage (shown in legend) and perceived shaking.
Population counts within a 50 mile radius of each nuclear power plant were calculated using the LandScan 2008 TM 30 arc-second Global Population dataset which is a statistical approximation of ambient or 24-hr day/night average population
SOURCE
Okay, so how old are some of these power plants now???
Because by my way of thinking --and no I am no scientist --but say after 50 yrs, would the ground shaking start to get worse???
Of course, this is out of my pay-grade, but we all know our infrastructure in general is outdated and dilapidated.
Cannot help but wonder the shape that these older power plants are in. And we know the 'check ups' aren't always, um, factual.
Could there be a connection???
Possibly.