(Reuters) - Two earthquakes, three monstrous hurricanes and the North Korean missile crisis have U.S. survivalists convinced that the end of the world is nigh. And they are clearing store shelves to stock bunkers in anticipation of Earth’s final chapter.

Situation room at Jerry McMullin's bunker has video conference servers in Yellow Jacket, Colorado, U.S. in this May 2012 photo released on September 21, 2017. Courtesy Jennifer Koskinen/Handout via REUTERS

Sales of freeze-dried food, gas masks and other survival equipment have spiked in recent weeks as so-called “preppers” get ready to ride out any disaster, whether natural or man-made.

Inspiring their actions: images of people helpless against floodwater from Hurricanes Harvey, Irma and Maria and island towns obliterated by their fury. People buried in rubble after earthquakes rattled Mexico. Footage of North Korea’s missiles blazing into the sky.

“It’s been a very busy six or seven weeks here - sales tripled practically overnight,” said Keith Bansemer, vice president for marketing for Idaho-based My Patriot Supply, an online store catering to preppper needs.

“It all started when North Korea shot the missile that was capable of reaching the U.S. Then the hurricanes and two Mexican earthquakes increased sales from California and Cascadia in the Northwest,” he said, referring to the corner of the country where many survivalists have settled because of its relative isolation.

David Yellin, a self-described prepper who lives in California’s San Diego County, said his main concern was the long-expected “big earthquake” along the West Coast.

The 31-year-old police officer has piled enough survival supplies in a closet of the apartment he shares with his fiance and their two dogs to allow them to hunker down for a month.

If disaster forces the couple to flee, each has a “bug-out bag” stuffed with three days of food, water, first aid and water purification supplies, fire-starting materials, a tent and sleeping bag, change of clothes and important documents.

At Ready To Go Survival, founder and chief executive Roman Zrazhevskiy said gas masks were quickly moving off the shelves and overall sales “are up like 700 percent over the last two months.”

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A prepper himself, he said his greatest fear was a U.S. economic collapse as a result of the country’s unsustainable debt.

“Once people go hungry, they are going to get to the streets and look for food,” said Zrazhevskiy, 31, who grew up in New York City’s borough of Brooklyn and now lives in Texas.

Customers were snapping up $500 CBRN suits to withstand chemical, biological, radiological and nuclear attack and $200 gas masks in sizes that fit children as young as 5.

“Gas masks? I’ve got tons of those,” said prepper Jerry McMullin, 62, a retired risk assessment analyst whose bunker-like home in Yellow Jacket, Colorado, was built to withstand nuclear attack, biological warfare and a range of natural cataclysms.

Although North Korea is one of his biggest concerns, McMullin is also worried about political instability in Washington leading to riots and mayhem in the cities, he said.

“I’m not a paranoid guy. I just want to be in a position that when it does go to Hell, I’m in a good location to get whatever I need,” said McMullin, who has his own water filtration system and burns his own trash in his solar-powered home.

In recent weeks, some doomsayers have expressed a belief that according to Biblical prophesy Saturday, September 23, would kick off seven years of catastrophic events that would lead to the end of the world as we know it.

David Meade, a Christian numerologist and author, has said that, based on the Book of Revelations, a constellation would appear over Jerusalem on Saturday that would start the seven years of mayhem.

But McMullin said his own respect for Bible prophesy assures him that disaster is not around the corner.

“As far as getting wiped out this weekend, I’m not too worried about that,” McMullin said.

“Maybe it’s a timeline marker and things are going to start getting really ramped up. We are not about to go through mass destruction and fatality. I think people are a little more stable - except for Kim,” he said, referring to North Korea’s President Kim Jong Un.

Preppers including Yellin and McMullin said images of people incapacitated by recent natural disasters left them feeling vindicated about the stockpiles they keep, which raise eyebrows among those who consider their planning extreme.

“I’m more of what I consider a common sense prepper,” Yellin said. “Because at the end of the day, we are responsible for our own safety.”