I'll blow my partial cover to state my credibility or lack thereof: I am Christopher "Chris" Sorlien and I am a research geologist at the University of California Santa Barbara. I live in the midwest though; that is why I am up early posting. I work on faults and folds including active faults and folds, using seismic reflection data and geologic information such as core information. I work on offshore southern and south-central California (and have worked onshore there in the past), Marmara Sea Turkey (North Anatolian fault), offshore Haiti, and Ross Sea Antartica. I am not a "seismologist", but as a geologist know quite a bit about earthquakes.

OK, following on my post above:
Yes, there will be large aftershocks, and there has already been a M7.1. And, yes, there was a M7.2 on March 09 that was a foreshock to this one. And, yes, Great earthquakes are known to trigger smaller ones at great and small distances.

But, I am not aware of global great subduction earthquakes being followed by Great earthquakes on the adjoining part of the subduction zone. It seems likely that the date of some future quake on the subduction zone to the south, closer to Tokyo, might be advanced, but if such a quake would not have occured for decades in the future, it still will not occur for decades in the future.

Most relevant is what happened in Japan in 1944: there was a M8.1 quake followed by another M8.1 in 1946 (link).

So, once they get things under control in Japan, yes, they do have to think about what failed this time and what they urgently need to work on (for example, we will learn more as the day goes on about cooling systems for nuclear power plants).

Chris

• 1944 and 1946 quakes