The Japanese earthquake has been upgraded. Most seismologists are now classing it as a 9.0. A 'megaquake'. A once in a thousand year event if we're really unlucky.
An earthquake is a release of pressure. The faults in the earth's crust rub against one another or duck under each other. As long as the fault moves smoothly, everything goes well. It's when it gets stuck that problems cause. Pressure builds up until something gives...and you get an earthquake.
The vast majority of earthquakes are no big deal. Most people can feel an earthquake of 3.0 or greater...providing they are not in motion at the time (people walking have been known to completely miss a 7). An earthquake has been compared to a 'freight train'...mostly because that's what an earthquake sounds like. Yes, I do know this from experience.
It's common wisdom that small quakes lower the risk of larger ones. Truthfully, though, there would have to be a lot of small quakes. As in hundreds of thousands of them.
But what if there were? What if, like back burning to prevent a major fire, we could somehow *create* those large numbers of small quakes. Or find some other way to constantly release the pressure of fault lines, to keep them moving smoothly. It seems insane. We can't even, right now, properly predict earthquakes. Preventing them is blue sky in the extreme.
But hey. I'm a science fiction writer. Blue sky is what I do.