Media Coverage of Tsunami vrs. Sudan
The video clips of waves washing into costal cities and luxury resort hotels are very dramatic. There is no video of the Sudanese holocaust (does this word apply?)
Another factor is familiarity. In two years, the death toll of Americans from car crashes is about the same as the tsunami death toll. More Americans died in car crashes in Sept. 2001 than from the WTC attack. In two years the death toll of Americans from car crashes is more than the number of Americans killed in Vietnam. I would guess that nearly every adult has lost at least one friend or relative to a car crash. Yet people are fairly blasé about it.
The last factor is the ability to identify with victims. The Isreali-Palistinian conflict is controversial because different people identify with different sides. Tsunami victims who are American or European decent get more attention than victims who were born there. The Sudanese massacres involve Arabic speaking black Africans and non-Arabic speaking black Africans. Most Americans don't identify with either group so people care less, as shallow that may seem.