When an earthquake in Japan is reported overseas, the problem is that they only report the magnitude of the epicenter (usually offshore). They don’t usually report the magnitude in the populated areas. This is actually more important than the epicenter’s magnitude (unless the epicenter is under a populated area). A magnitude 6+ quake was reported today. That’s very strong, but it was only magnitude 3 in Tokyo. If it were magnitude 6 in Tokyo, we might have some damage and injuries. To find out the intensity of the affected prefectures, check this: http://www.jma.go.jp/en/quake/quake_singendo_index.html
Click on the time when the quake occurred, then you can see a map of the prefectures which were affected and their color-coded intensity. Magnitude 4 or lower is minor. Here’s the map of the one we got tonight at 9:06 pm: http://www.jma.go.jp/en/quake/3/20120314210927484-142105.html