Harold Camping has never been to New Zealand and is rather sad he won't be able to visit before the end of the world. "I'm sorry it's too late," he says.

The 89-year-old preacher from Oakland, California, is convinced Judgment Day is coming on May 21 when the world will be shaken by a violent earthquake, graves forced open, the bodies of sinners strewn about and true believers called to heaven to live with Christ forever, he says.

His followers in Wellington and elsewhere will be praying quietly at home rather than flocking to churches as the clock ticks down - they're not big on organised religion.

Camping is a former civil engineer who runs Family Radio, a religious broadcasting organisation that owns 66 stations in the US and broadcasts in Taiwan, Indonesia, Vietnam and the Philippines. He has issued his grim warning to New Zealand and dozens of other countries, including Ethiopia, Chile and Poland, by means of a worldwide billboard campaign.

On the phone from Family Radio HQ in Oakland, Camping says he is keeping busy during earth's last days. "I'm trying to keep my nose to the grindstone to warn the world that Judgment Day is coming," he says.

He expects to watch it unfold on television as the massive earthquake hits New Zealand first - about 6pm on May 21 - then gradually rolls around the world.

Camping says he has reached his conclusion after more than 50 years of Bible study, applying mathematical calculations to the prophecies. He views the killer tornadoes in the States, major earthquakes in Japan, Haiti and Christchurch and floods as well social movements like gay pride as "grim reminders" that the end is nigh.

Camping has not considered the possibility that the sun will rise as normal on May 22. "I can't think like that because the Bible is crystal-clear that it will happen," he says. "If I was trying to develop plan B it would mean that I'm not trusting the Bible."

His boldness in marking "apocalypse" on the wall planner may be unusual, but the prediction that the end-of-times is looming is hardly new. Peter Mortlock, pastor of Auckland's City Impact Church, thinks there is no doubt the day of reckoning is coming but it is "highly unlikely" to be this month.

Mortlock also points to earthquakes and changing weather patterns as signs the end is nigh. The best preparation, he says, is to be right with God. Mortlock doesn't dwell on damnation. "Fire and brimstone has connotations and in our PC world today, it's not nice to talk about these things."

In times of fear, people tend to seek comfort in religion. Mortlock says that in the weeks following 9/11, churches were packed and Christchurch congregations increased after the recent earthquakes. "I often say there are no atheists in an earthquake," says Mortlock. "When things like an earthquake happen, people call out to God."

Pastor Daniel McKibben of Royal Oak Seventh Day Adventist Church started a seminar series this week linking the global financial crisis, tsunamis, earthquakes, Japan's nuclear radiation leaks and unrest in the Middle East to biblical prophecies of Armageddon.

"I believe we are getting close to the time of the end but we can't put a date on it," says McKibben. And don't bother building a bunker. "I don't tell my people to store up food or store up water," McKibben says. "It's not going to prepare for us for the days we're talking about."

Whatever are you talking about, ask the scientists.

GNS Science seismologist John Ristau says there has been no increase in earthquakes in New Zealand. "It's the same as it's always been," says Ristau. "There is nothing unusual except in the Canterbury region with all the aftershocks from the earthquakes in September and February, but that's to be expected when you have a large magnitude earthquake."

United States Geological Survey, a science agency of the US Government, says earthquakes of magnitude 7.0 or greater have remained fairly constant throughout this century. It attributes the perceived increase in earthquakes to more seismological monitoring, improved global communications and an increase in population density.

Imminent Armageddon is a recurrent theme throughout history. Associate professor Peter Lineham from Massey University, an expert on religious history, says it surfaces whenever times are troubled. And there are also versions in Judaism and Islam.

Napoleon Bonaparte was considered the anti-Christ in Britain, Jews drew on apocalyptic language to explain the Holocaust and, in today's Islamic world, America is often portrayed as a great evil. These fears are always present, says Lineham.

While Christ's second coming appeals to some, the concept of an environmental apocalypse is gaining traction with others. Jason Kerrison, the lead singer of chart-topping rock band Opshop, has set up a group to raise awareness of December 21, 2012, as "the end of the great cycle".

According to Kerrison and others the significance of this date is marked in the calendar of the Mayan people, an ancient South American culture.

The West Auckland rock singer does not know what to expect, but thinks possibilities include coronal mass ejection activity (massive bursts of solar wind), shifts in the earth's magnetic field and earthquakes.

"We thought if we could contribute in any way it was to shift the conversation from being fear-based to a state of preparedness," says Kerrison.

The 38-year-old is building a bunker, an enormous structure he calls "The Ark" that he is burying on his Far North farm, "as far away from a large faultline as it can possibly be and the highest it can be."

He and his wife Cassie have a pact of secrecy about its exact whereabouts - presumably, when the thunder rolls and the ground sharts shaking, they don't want their apocalypse party to be spoiled by gatecrashers.

Kerrison's Ark is being built by Hardened Structures NZ Ltd, the Taupo-based arm of a big American company that specialises in designing and building bunkers to shelter wealthy corporate and private clients from nuclear, chemical and biological warfare, earthquakes and - yes - the 2012 apocalypse.

Company director Tony Walden, of Herne Bay, says the market for 12m domes, pods, bunkers and reinforced rooms has been growing.

"A lot of it is a fear of anarchy, that if something does happen they want to be able to protect their family from looting," he says. "We don't get involved in what they're preparing for. We just ask about their needs, then custom-tailor a solution."

The company website warns of the potential for a coronal mass ejection similar to that of September 1859, which disoriented compasses and damaged telegraph networks.

Another such event would knock out national power grids for between two and 10 years, Hardened Structures warns grimly. Water supplies would run out in 48 hours, food supplies would run out in three days and civil unrest would occur within seven days.

"From our perspective as architects, engineers, physicists and construction programme managers," the website says, "we view the 2012 phenomenon not as a question of the accuracy or validity of the Mayan date, but as a problem of shelter design optimisation under severe constraints."

The language used by Kerrison and Hardened Structures sounds more scientific than Camping's, but their expectations are much the same. Those who are prepared - physically or spiritually - will be saved. Those who aren't risk destruction.

"It's all part of a rebirth," says Kerrison. "As with most birth there is pain and there is blood and there is new life. I would rather have an optimistic approach than a fear-based mentality."