Among the big shake-ups on the Social 50 chart this week: Avril Lavigne and Taylor Swift vault into the top 10 while Slayer debuts straight in at No. 18.

Lavigne zips 21-8, marking her first visit to the top tier, seemingly basking in the glow of the debut of the music video for "What the Hell" on Jan. 24. Its official clip on YouTube has been viewed nearly 7 million times. Lavigne saw a 376% gain in week-over-week new Facebook fans and a 302% jump in her YouTube channel views.

Avril Lavigne Strips Down, Goes Bad in 'What The Hell' Video

Swift returns to the top 10 after a week's absence, running 14-9 as her "Back to December" song and video continues to make headway on the charts. "Back" rises 22-14 on the Billboard Hot 100 -- its first visit to the top 20 since it debuted at No. 6 on the Oct. 30, 2010, chart. On the Pop Songs airplay tally, it bullets 15-12.

Taylor Swift Braves Breakup in 'Back To December' Video

As for the rest of the top 10, Justin Bieber, Rihanna and Akon are steady at Nos. 1-3, respectively, while Lady Gaga rises one to No. 4. Shakira jumps 10-5, Katy Perry and Eminem both fall one each to Nos. 6 and 7, respectively. Rounding out the top 10 is Michael Jackson, who slips one to No. 10.

Metal legends Slayer arrive at No. 18 after the band posted massive gains in Facebook fans and Twitter followers last week. Figure that the jumps are owed to the recent announcement of the Big 4 concert featuring the band with Metallica, Megadeth and Anthrax on April 23 in Indio, Calif. While all four of the bands saw increases in Facebook fans, Slayer benefitted the most -- going from less than 500,000 fans to nearly a million in in the course of a week.

Bob Marley earns a handsome jump up the list, climbing 37-20 with a 56% gain in new Facebook fans and a 25% increase in Twitter followers. The surge is perhaps owed to the publicity surrounding the Feb. 1 release of his new "Live Forever: the Stanley Theatre" set.