Longest series ever. I've been writing in snatches between festivities.
Natural seeps may be very well and good, but what if you want to create a New New Madrid in a hurry? You inject surface water directly into the Precambrian and upset all that balance. The fascinating thing about earthquakes is their chaotic nature. And you never know the initial conditions. Yeah, that makes them impossible to predict on the fine scale required for humans. You can predict that if you inject you will get earthquakes, but you'll never know how big and how soon.
Initial conditions depend on earthquakes past, and so a minor seep such as Virginia can almost instantly produce an M6 from a dammed lake. The M5.6 Oklahoma happened quickly, as well. That is to say, the fault was all primed up and Ready to Rumble.
On the other hand, you can have something as slow as the main OK mechanism. Massive injection of billions of barrels of water has only brought things to M4.8 so far. That means the area may be generally destressed. Earthquakes are also fascinating in that they are self-similar (fractal) between two limits - the very large, and the very small (grain size). So, if you looked at a picture of fractured rock, you wouldn't be able to tell the scale, unless there was a scale, like a person standing in front of it. Some satellite photos look like they were taken with a magnifying glass.
This self-similarity produces the classic straight log-log plot between Magnitude and frequency of occurrence. So, there are a lot of little earthquakes for one of the next bigger size. The slope of this curve is related to fractal roughness. OK has a high fractal roughness, and California is probably very low.
OK has developed a full mechanism, just like New Madrid. We just don't know how long it will take to get to M7's. At any time we could have a 7 or it may take decades. The same is true for the natural seeps, such as Toronto. Who knows? It would be prudent for all these areas to have a good earthquake plan, but they just go on and party. Ce la vie!
ps. I just put a complete version, with links, in Geofish Clarified.