Seiichiro Nishimoto, CEO of Shelter Co., wearing a gas mask in a model room for the company's nuclear shelters. Kim Kyung Hoon/Reuters A rising number of American billionaires are channeling their inner Bear Grylls — some in preparation for an apocalyptic event, be it a viral epidemic, nuclear war, or cataclysmic pole shift.

Reid Hoffman, the cofounder of LinkedIn and a notable investor, told The New Yorker earlier this year he estimated that more than 50% of Silicon Valley billionaires had bought some level of "apocalypse insurance," like an underground bunker.

A new article in Forbes suggests the superrich are making significant land grabs in America's heartland, where the climate is mild and the locations are conducive to survivalism, farming, and living on the land. States like Colorado, Montana, Nebraska, New Mexico, North Dakota, Texas, and Wyoming are home to several fortified shelters and vacation homes where wealthy billionaires could happily live out their post-doomsday (or retirement) days.

According to Jim Dobson, a Forbes contributor, lots of billionaires have private planes "ready to depart at a moment's notice." They also own motorcycles, weaponry, and generators.

None of the billionaires named by Forbes has said publicly that their vast amounts of land would be used for apocalypse preparations — though they certainly would make good hideouts.

John Malone, who made his fortune in cable and communications, is the nation's biggest individual landowner with 2.2 million acres across six states, including huge swaths of Maine and New Hampshire. Malone told Forbes in 2011 that he made the land grabs as an investment. He said he loves to fish and occasionally hunt birds on his properties.

The media mogul Ted Turner, the second-biggest individual landowner in the US, owns 2 million acres across Colorado, Kansas, Montana, Nebraska, New Mexico, and South Dakota.

Philip Anschutz, a railroad and oil magnate, locked down 434,000 acres in Wyoming. Amazon's Jeff Bezos has 400,000 acres in Texas. And Stan Kroenke, the owner of a massive sports-and-entertainment holding company, bought 225,000 acres in Montana.

One of the more surprising real-estate tycoons is David Hall, a Mormon engineer, who has been snapping up farmland in Vermont. He wants to build sustainable, high-density communities based on the writings of the religious figure Joseph Smith.

In the event of the end of the world, the world's financial leaders may be the most prepared.