If you spend much time watching the cable news channels, try this: During an epic disaster somewhere else in the world, flip back and forth among FOX, CNN and MSNBC. FOX will more often than not be covering a domestic story or angle, usually political (partially because they don't have the correspondents where they need them but mostly because IMHO their unspoken mission statement is to focus on American stories), hence I saw more on FOX in a couple days of channel surfing after the Japan earthquake about the American swept away on the California coast and affects on Hawaii than about Japan.

I can't imagine FOX was caught short-handed in Japan the way they were in Egypt and Libya (at least I can only presume since they didn't cover them well), so the only reason would be they think the stories they did cover were more important, drew more viewers, attracted more advertisers, satisfied network leadership, or met broadcast standards the rest of the world doesn't have.

A quick search found a report that CNN viewers rose 172% during disaster coverage while FOX rose only 46%:

http://www.realtvcritics.com/reviews/cnn-fox-news-viewership-jumps-with-japan-earthquake-coverage-video/

More #'s I don't totally understand but show CNN clear winner:

http://tvbythenumbers.zap2it.com/2011/03/15/cable-news-ratings-for-saturday-sunday-march-12-13-2011/85825

I actually saw FOX covering the Wisconsin/labor controversy with the Wisconsin governor instead of the earthquake, during Hannity I think. I understand how important that must have been for them, since conservatives suffered a (deserved) thrumming from most outlets, but the contrast between what FOX was covering and nearly every other news source was enlightening.

The choice of what you cover is just as important as what you say.