"Remember the Richter scale is base-10 log scale. The aftershocks are nearly the same magnatitude as the Sylmar quake and other destructive ones in Calif."
The Richter scale is no longer used by the world's geologists. When they talk of magnitude, they are usually referring to the Moment Magnitude scale. however I believe (though am not certain) that the Japanese use a slightly different scale again. In all scales, the error of accuracy is at least +/- 0.2, so call the Japanese quake between 8.8 (which is what the Japanese have been quoting) and 9.2. No matter how you measure it, it was a huge seismic event at the focus, and the tsunami results are truly mind-boggling. However, I will stress again, the shaking felt, whether 130km in Honshu, or 380km in Tokyo, is much less than even the Sylmar quake. Keep in mind the Sylmar quake was named for it's epicentre because the epicentre was on land, whereas the current Japanese quake is named by the town/region closest to the epicentre, which is 130km away. And also note the difference in peak ground acceleration (aka Near Source, or near Fault, i.e. near the focus/epicentre): Northridge being a very strong 1.7g (I don't know if they used this measurement when the Sylmar quake occurred but it is quite clear from the damage that it was pretty high), Honshu being only about 0.35g. The Sylmar was a strike/slip type of moveement, which is generally more more damaging than a subduction movement, given equal momentums. The Sylmar had a Modified Mercalli rating of MM8-9, compared to the rating of MM6 for Honshu and MM5 for Tokyo. In other words, just because it was ~9.0 at the focus doesn't mean you feel an equally strong shock in California. Distance from event, peak acceleration, type of media the seismic waves move through, and local geology all have a huge impact on how an earthquake is felt and what damage it does. At the distances from the epicentres I've seen, the aftershocks (nor the main shock) are not anywhere near what the magnitude is. The only frightening aftershock is one you feel, and if it's a 7.0 130km away, it may only be a slight fraying of the nerves. I would love to hear from anyone in the vacinity of these events to comment on how it felt. Not the tsunami, I mean the shaking and aftershocks.
Basically I'm trying to get folks to understand the difference between "Magnitude" of an earthquake and "perceived shaking or damage" where you happen to be standing on this planet relative to that earthquake.