Google webmaster tools added new automated alert about traffic change when specific webpage traffic suddenly increase. The message will be appear as a alerts after sign in Google webmaster tools. See the traffic change notification message screen shot.
In message text your website address and ‘Big traffic change for top URL’ title will appear. Full message description will be ‘Search results clicks for http://www.yourwebpage.com/yourlinke.html have increased significantly. Yay! with message id’.
Already Google panda started to notify via message for low quality webpages in webmaster tool. Specially for poor and not using unique content. Now this new notification about traffic, I assume that Google is in full mood to display only spam free and content rich results in search engine.