A man has multiple backup plans in case of a terrorist attack on nuclear power plants; a farming family prepare for a series of F5 tornadoes by building an underground habitat for their animals and stockpiling medication; a retired couple who fear that Greenland's ice sheet will melt relocate to Texas and build a self-sustainable property.

Source: National Geographic Channel

A former motocross racer prepares his family for a terrorist smallpox attack in the Season 2 premiere. Also: A musician gets ready for a nuclear attack by building an underground bunker; a 15-year-old who has been prepping since he was 11 stocks up on weapons and food in case of an economic disaster.

Source: National Geographic Channel

A former law-enforcement officer prepares for a global crisis by making his own pepper spray; a small-business owner barters for goods ahead of an expected earthquake; a real-estate investor purchases a plot of land in Upstate New York and plans to hide out there if World War III begins.

Source: National Geographic Channel

A man makes prepping for a terrorist attack his full-time job by stocking up on supplies, teaming up with an ally who assesses contaminated sites, and checking radiation levels in his home.

Source: National Geographic Channel

A full-time prepper anticipates a deadly volcanic eruption; a couple take steps to prepare for a breakdown of the world's food system; an inventor secures his home against disaster.

Source: National Geographic Channel

A California man preps for widespread environmental damage from an earthquake by growing edible plants and training his 12-year-old daughter in self-defense.

Source: National Geographic Channel

Three New York City residents plan escape routes for emergency evacuations. Included: A Hurricane Katrina survivor aims to walk hundreds of miles away from the city; a college student preps for a paddling trip across the Hudson River to New Jersey; a stock trader plans to get his family to a safe house in the event of a terrorist attack.

Source: National Geographic Channel

A Florida businessman builds a medieval-style castle to protect his family in the event of an electromagnetic pulse.

Source: National Geographic Channel

A Florida businessman builds a medieval-style castle to protect his family in the event of an electromagnetic pulse.

Source: National Geographic Channel

Preppers protect themselves against disaster by forming tight-knit communities.

Source: National Geographic Channel

Visiting the remote mountain home of a prepper who claims she received a warning of imminent danger in a dream.

Source: National Geographic Channel

Two motorcyclists set up a homestead in the Virginia mountains in case of an economic collapse; a construction-company owner in Maine prepares for disaster; a man spends his time in his mobile home, which he plans to use as a hideout in the wake of a terrorist attack.

Source: National Geographic Channel

A prepper looks for love while building a bunker out of a decommissioned missile silo. Elsewhere, a stone-quarry owner creates a haven out of rocks.

Source: National Geographic Channel

An Alaska man builds a bug-out dome that's only accessible by boat; a new-age spiritual prepper in Hawaii prepares for a destructive tsunami.

Source: National Geographic Channel

A family who live near Mount St. Helens make safety arrangements in case of an eruption; a prepper intends to use his sailboat as a bunker if disaster strikes.

Source: National Geographic Channel

A Virginia couple worry that political tension and economic unrest will result in a world war; an Oregon man prepares for a terrorist attack; an unconventional Kansas resident eschews modern conveniences.

Source: National Geographic Channel

A couple protect themselves against an economic collapse by stockpiling canned goods, weapons and supplies, but they still need an underground bunker. Elsewhere, a well-off family plan to hide out in Costa Rica.

Source: National Geographic Channel

A look back at highlights from Season 2.

Source: National Geographic Channel