8.4 Quake hits Japan

Does anyone have information where is the worst hit area?

Tohoku region, around Sendai. But the damages are quite widespread - some areas close to ports and rivers (along the Pacific coast of Tohoku region) have been hit by tsunami.

Here are some basics:
http://www.japan-guide.com/news/0018.html

Here in Yokohama, phones were out of order for a while, and then it was in order, and then it got out of order again along with the internet. But when I finally went to the supermarket after the tremors calmed down, everything was normal except for the long queue at the pay phone.

So if you have friends or family in which you can't contact, it's probably just because of line disorder, and they're likely to be fine.

Those living in Japan, however, is strongly warned to stay away from the sea or river or any kind of water, almost wherever you are.