Earthquake map -- Focus on Japan

[Art_from_Ark]

16. I think the seismic activity around the reactor area was much worse last March and April

when there were numerous "aftershocks" of magnitude 6.0 or higher in the immediate vicinity. Recent activity specific to the Hamadori area of Fukushima (where the reactors are located) has been relatively mild (although much more active than before the March 2011 earthquake).

The impact of the recent 5.1 earthquake centered in northern Ibaraki (the Hitachi area, about 40 miles or so south of the complex) was very local, with a top Japanese seismic intensity level of 5- (possibility of some heavy damage) limited to the Hitachi/Northern Ibaraki area, with the Fukushima Dai-ichi complex registering an intensity of 2 (slightly noticeable shaking).

One thing to bear in mind here is that the "intensity", as it is used in the link you provided, is not the same as "magnitude". There, "intensity" refers to the system that the Japanese use to evaluate the potential for seismic damage. It can be confusing, especially in this case where the maximum Japanese intensity level of 5- coincided with the magnitude of 5.1.