It is said that the term "supermoon" was first used at the website of a Richard Nolle, an astrologer, who stated that moon will be 90% of its closest distance (perigee) from the earth surface and it is maximum to the perigee on March 19, 2011, which is a supermoon.

The statement that the earthquake on March 11, 2011, in Japan is a cause of supermoon is incorrect due to two reasons:
1. The moon is not relatively close (at perigee) to earth on March 11, 2011. In fact it is more closer on March 19, 2011.
2. It is neither a full moon nor a new moon (alignment of moon with the sun and earth). In fact, the moon is at a right angle to the earth and sun. The effect of moon’s gravity on earthly waters and rocks is least and therefore the effect on the magnitude of tidal waves on earth will be the least.

The statement that a supermoon caused the December 26, 2004, tsunami in Indonesia is also incorrect. More than 200,000 people lost their lives in that tsunami. It was a full moon and but not a supermoon. In fact, it was at its farthest distance from earth. The moon was closest two weeks after, January 10, 2005.

On March 19, 2011, the full moon will be a close one. There is however no scientific grounds that it will cause any sizable effects on earth's water. Moreover, the earth has been more closer to moon than it will be on March 19, 2011. So, there is really no need to panic by the "supermon" theory.

source:http://earthsky.org/water/whats-true-and-false-about-the-march-19-supermoon
Image source:http://t2.gstatic.com/images?q=tbn:ANd9GcR59qFDx_SD-toqfpQsu3q4bFD1fvx8cd0BOAlJwUmQPNI0Qb3T

To see it on the Internet, the so-called supermoon could cause a climatological reign of terror on the entire planet. Although it’s more than a week away, some people say the devastating 8.9-magnitude earthquake that hit Japan today could be the latest natural disaster caused by it.

The 2005 Indonesian tsunami hit two weeks before the supermoon and for the 2011 supermoon, which is suppose to occur March 19, the moon won’t just be at its closest approach to Earth in its elliptical orbit, enthusiasts say, it will be closer to Earth than it has been in 18 years.

Scientists like Paul Walker, senior meteorologist for AccuWeather Inc., say there is no connection between the moon’s position and Japan’s earthquake.

“I don’t think you can attribute it to being a full moon, which is still eight days away,” Walker said. “These moon events can cause the tides to run higher than normal, but I’ve not heard of any correlation between them and extreme weather events.”

Where Did ‘Supermoon’ Come From?

AccuWeather blogger Mark Paquette said he thinks the phrase “supermoon” originated on the website of astrologer Richard Nolle and spread to astronomers online.

In a blog post earlier this month, Paquette said a new or full moon at 90 percent or more of its closest perigee qualifies as a “supermoon.” The moon’s orbit around us is slightly elliptical, and when the moon is at the near point, it is known as a lunar perigee.

Next weekend’s full moon won’t just be a supermoon but an extreme supermoon, he said, because the moon will be almost precisely at its closest distance to Earth.

According to “new age” forecasts, he said, the supermoon brings strong earthquakes, storms or unusual climate patterns.

“There were supermoons in 1955, 1974, 1992 and 2005,” he wrote. “These years had their share of extreme weather and other natural events. Is the Super Moon and these natural occurrences a coincidence?

“Some would say yes; some would say no. I’m not here to pick sides and say I’m a believer or non-believer in subjects like this, but as a scientist I know enough to ask questions and try to find answers.”