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On March 19, the moon will swing around Earth more closely than it has in the past 18 years, lighting up the night sky from just 221,567 miles (356,577 kilometers) away. On top of that, it will be full. And one astrologer believes it could inflict massive damage on the planet.

Richard Nolle, a noted astrologer who runs the website astropro.com, has famously termed the upcoming full moon at lunar perigee (the closest approach during its orbit) an "extreme supermoon."

When the moon goes super-extreme, Nolle says, chaos will ensue: Huge storms, earthquakes, volcanoes and other natural disasters can be expected to wreak havoc on Earth. (It should be noted that astrology is not a real science, but merely makes connections between astronomical and mystical events.)

But do we really need to start stocking survival shelters in preparation for the supermoon?

The question is not actually so crazy. In fact scientists have studied related scenarios for decades. Even under normal conditions, the moon is close enough to Earth to make its weighty presence felt: It causes the ebb and flow of the ocean tides.

The moon's gravity can even cause small but measureable ebbs and flows in the continents, called "land tides" or "solid Earth tides," too. The tides are greatest during full and new moons, when the sun and moon are aligned either on the same or opposite sides of the Earth.

According to John Vidale, a seismologist at the University of Washington in Seattle and director of the Pacific Northwest Seismic Network, particularly dramatic land and ocean tides do trigger earthquakes. "Both the moon and sun do stress the Earth a tiny bit, and when we look hard we can see a very small increase in tectonic activity when they're aligned," Vidale told Life's Little Mysteries, a sister site to SPACE.com.

At times of full and new moons, "you see a less-than-1-percent increase in earthquake activity, and a slightly higher response in volcanoes."

The effect of tides on seismic activity is greatest in subduction zones such as the Pacific Northwest, where one tectonic plate is sliding under another. William Wilcock, another seismologist at the University of Washington, explained: "When you have a low tide, there's less water, so the pressure on the seafloor is smaller. That pressure is clamping the fault together, so when it's not there, it makes it easier for the fault to slip."

According to Wilcock, earthquake activity in subduction zones at low tides is 10 percent higher than at other times of the day, but he hasn't observed any correlations between earthquake activity and especially low tides at new and full moons. Vidale has observed only a very small correlation.

What about during a lunar perigee? Can we expect more earthquakes and volcanic eruptions on March 19, when the full moon will be so close?

The moon's gravitational pull at lunarperigee, the scientists say, is not different enough from its pull at other times to significantly change the height of the tides and thus the likelihood of natural disasters. [Infographic: Phases of the Moon Explained]

"A lot of studies have been done on this kind of thing by USGS scientists and others," John Bellini, a geophysicist at the U.S. Geological Survey, told Life's Little Mysteries. "They haven't found anything significant at all."

Vidale concurred. "Practically speaking, you'll never see any effect of lunar perigee," he said. "It's somewhere between 'It has no effect' and 'It's so small you don't see any effect.'"

The bottom line is, the upcoming supermoon won't cause a preponderance of earthquakes, although the idea isn't a crazy one.

"Earthquakes don't respond as much to the tides as you'd think they would. There should actually be more of an effect," said Vidale.

Most natural disasters have nothing to do with the moon at all. The Earth has a lot of pent up energy, and it releases it anytime the buildup gets too great. The supermoon probably won't push it past the tipping point, but we'll know for sure, one way or the other, by March 20.

This story was provided by Life's Little Mysteries, a sister site of SPACE.com.

Cue 8.4 earthquake in Japan.

Awful news that earthquake.
8.x is very heavy.

BBP wrote:Cue 8.4 earthquake in Japan.

8.9 is what I believe they set the final. That said, it's not March 19th, so the moon can't be blamed.

There was a warning here on the west side of Vancouver Island. That's not the same thing as Vancouver. Yeah, it's weird.

Here's Vancouver Island in relation to the rest of British Columbia. As you can see, Vancouver (the city) is to the east of the island on the mainland itself.

There was also a warning in San Diego (and Los Angeles) which proved to be 2 foot waves.

Which is almost less than normal. But the danger I guess was when the tide receded if people went out - then when the tide suddenly came back in.

This story was updated at 3:32 p.m. ET.

Thanks to a fluke of orbital mechanics that brings the moon closer to Earth than that it has been in more than 18 years, the biggest full moon of 2011 will occur on Saturday, leading some observers to dub it a "supermoon."

On Saturday afternoon at 3 p.m. Eastern Daylight Time, the moon will arrive at its closest point to the Earth in 2011: a distance of 221,565 miles (356,575 kilometers) away. And only 50 minutes earlier, the moon will officially be full.

At its peak, the supermoon of March may appear 14 percent larger and 30 percent brighter than lesser full moons (when the moon is at its farthest from Earth), weather permitting. Yet to the casual observer, it may be hard to tell the difference.

The supermoon will not cause natural disasters, such as the Japan earthquake, a NASA scientist has stressed.

Spotting the supermoon

The moon has not been in a position to appear this large since March 1993.

In December 2008, there was a near-supermoon when the moon turned full four hours away from its perigee – the point in its orbit that is closest to Earth. But this month, the full moon and perigee are just under one hour apart, promising spectacular views, depending on local conditions.

Although a full moon theoretically lasts just a moment, that moment is imperceptible to ordinary observation.

During the day or so before and after, most will speak of seeing the nearly full moon as "full," with the actual shaded area of the lunar surface being so narrow – and changing in apparent width so slowly – that it is hard for the naked eye to tell whether it's present, or which side it is.

Supermoon making waves

In addition, the near coincidence of Saturday’s full moon with perigee will result in a dramatically large range of high and low ocean tides.

The highest tides will not, however, coincide with the perigee moon but will actually lag by up to a few days depending on the specific coastal location. For example, in Wilmington, N.C., the highest tide (5.3 feet) will be attained at 11:21 p.m. EDT on March 20.

In New York City, high water (5.9 feet) at The Battery comes at 10:49 p.m. EDT on March 21, while at Boston Harbor, a peak tide height of 12.2 feet comes at 1:31 a.m. EDT on March 22, almost 2 1/2 after perigee.

According to the Observer’s Handbook of the Royal Astronomical Society of Canada, residents of regions along the shores of the Bay of Fundy in eastern Canada, the 10- to 20-foot (3- to 6-meter) swell in the vertical tidal range makes it obvious when the moon lies near perigee, regardless of clear skies or cloudy.

Any coastal storm at sea around this time will almost certainly aggravate coastal flooding problems.

Such an extreme tide is known as a perigean spring tide, the word spring being derived from the German springen – to "spring up," and is not, as is often mistaken, a reference to the spring season.

In contrast, later this year, on October 11, the full moon will closely coincide with apogee, its farthest point from the Earth. In fact, on that night the moon will appear 12.3 percent smaller than it will appear this weekend.

Big full moon's appearance is deceiving

And while this weekend’s moon will be – as the Observer’s Handbook suggests – the "largest full moon of 2011," the variation of the moon's distance is not readily apparent to observers viewing the moon directly.

Or is it?

When the perigee moon lies close to the horizon, it can appear absolutely enormous. That is when the famous “moon illusion” combines with reality to produce a truly stunning view.

For reasons not fully understood by astronomers or psychologists, a low-hanging moon looks incredibly large when hovering near trees, buildings and other foreground objects. The fact that the moon will be much closer than usual this weekend will only serve to amplify this strange effect.

So … a perigee moon, either rising in the east at sunset or dropping down in the west at sunrise might seem to make the moon appear so close that it almost appears that you could touch it. You can check out this out for yourself by first noting the times for moonrise and moonset for your area by going to this website. ( http://us.rd.yahoo.com/dailynews/space/ ... ne-year-us )

If you'd like to share your supermoon photos of the March 19 full moon, contact SPACE.com managing editor Tariq Malik: tmalik@space.com.

Joe Rao serves as an instructor and guest lecturer at New York's Hayden Planetarium. He writes about astronomy for The New York Times and other publications, and he is also an on-camera meteorologist for News 12 Westchester, N.Y.