WASHINGTON (AFP) - Whimsical TV disaster movie Sharknado 2 reeled in 3.9 million viewers, the Syfy specialty channel said on Thursday, one day after the sequel's broadcast.

The followup to last year's instant cult classic about a freak weather system that rains a torrent of man-eating sharks on New York City was also a massive hit on social media, at one point dominating the entire top-10 trending list on Twitter, Syfy said.

"Sharknado 2 is the most social movie on TV ever, and was more social than any episode of Game Of Thrones, The Bachelorette or Survivor," it added in a statement.

The Nielsen ratings service put the number of Sharknado 2 tweets at 581,000 - way ahead of America's Got Talent, the summer's most popular TV series among Americans, with 59,000.

The original Sharknado, set in Los Angeles, drew 1.4 million viewers and prompted 318,000 tweets - key numbers in an era when social media engagement is as important for TV executives as eyeballs glued to the screen.

An unabashed homage to the B-movies of Hollywood's Golden Age, Sharknado 2 starred Beverly Hills 90210 alum Ian Ziering and Tara Reid from the American Pie films.

Syfy, a unit of NBC Universal, has already commissioned a third movie in the franchise, showbiz trade journal Variety reported.