Google released a blog post on the traffic spike
The spike in searches related to Michael Jackson was so big that Google News initially mistook it for an automated attack. As a result, for about 25 minutes yesterday, when some people searched Google News they saw a "We’re sorry" page before finding the articles they were looking for
Google has not mentioned the exact amount of traffic they received but they released this graph to show the change in the volume
Meanwhile a blog post on Yahoo says
The passing of the King of Pop set multiple records across Yahoo!. On our front page, the story “Michael Jackson rushed to hospital” was the highest clicking story in our history. It generated a whopping 800,000 clicks within 10 minutes and news of his death saw 560,000 clicks in 10 minutes. Also, the news area on our front page experienced five times the amount of traffic it normally receives.
Facebook too recorded huge amount of conversations on Michael Jackson and they released this graph
Is the Web Ready To Handle Emergency? Yes, At Least The Search Giants and Social Networking Sites
This event has proven that Google, Yahoo & Facebook are capable of handling huge amounts of unexpected traffic. If there is an emergency in the future, these sites would remain useful system for people seeking credible information about what is going on.