Google Mayday Update and SERP Changes : 

Recently, however, many SEO professionals have detected dramatic drops in organic search results from certain keyword phrases with multiple words, known as “long tail” keywords Keyword phrases that are 3 or more keywords long or “fat belly” keywords. Fat Belly is more like 2 or 3 keywords in a query, long tail is normally a bit longer.

Interestingly, while many are crying foul, others contend that the MAYDAY phenomenon started happening as much as a month ago, or that it can’t even be pinned down as an algorithmic change. Google hasn’t confirmed or denied an algorithm update.

Google makes periodic adjustments to its algorithm that determines organic search results. It likely does this each day, using small adjustments, to avoid large-scale mayhem that infrequent adjustments would presumably cause.

SEO professionals have called this recent drop in traffic the “MAYDAY” algorithm update, and it made waves in SEO forums last week, with site owners lamenting large drops in their long tail traffic.

Google did update its design this month  to move to the two-column search results format used by other major engines. But, a design change does not necessarily signal a sudden algorithmic update. The design change increases the likelihood of searchers using other forms of vertical search, like images and video, giving marketers who optimize for those verticals a leg-up.