I think Terence Tao is one of the few professors in mathematics for whom the professorship market is truly liquid, and his salary history reflects that. His salary has skyrocketed to over $430k:
All the faculty getting paid more than him tend to be physicians and surgeons.
For comparison, the average pay of a tenured professor at Harvard (highest paying university on average) is "only" $198k: http://www.thecrimson.com/article/2013/4/10/harvard_salaries... Tao isn't even at Harvard and he's paid over double the average for tenured faculty there. I can only assume UCLA is forced to match what he could get if he left to a place like Harvard.
Terrence Tao is a far stronger "get" than the average Harvard professor.
He is brilliant mathematician, eloquent educator (from introductory to proffesional topics), and a thought leader (with Gowers) in the mathematical research community on meta topics like research style.
Of course, that's the point. It takes such talent in academics to command the sort of job liquidity at the high end that is taken for granted in industry.
That Terence Tao is being paid twice the average tenured salary at Harvard while he's at UCLA speaks to both our points. Unlike most professors, Terence Tao is paid by UCLA what he could hypothetically get if he went to Harvard (speculatively, of course). Other professors would face much more friction in packing up their bags and hopping into tenured positions at peer institutions or higher.
http://ucpay.globl.org/index.php?campus=&name=Terence+Tao&ti...
All the faculty getting paid more than him tend to be physicians and surgeons.
For comparison, the average pay of a tenured professor at Harvard (highest paying university on average) is "only" $198k: http://www.thecrimson.com/article/2013/4/10/harvard_salaries... Tao isn't even at Harvard and he's paid over double the average for tenured faculty there. I can only assume UCLA is forced to match what he could get if he left to a place like Harvard.