Lunar Perigee will occur on March 19th, 2011 and refers to the fact that this is the closest the moon has ever gotten to the earth in the last 18 years. The actual distance between the moon and the earth on that day will be 356,577 km.
Concerns arise as a closer moon could mean more tides including so-called earth tides - actual shifting of the earth surface under influence from the moons proximity. Similar to water tides, these could technically cause enough shift of the earth’s surface to set of earthquakes and volcanoes.
Some astronomers are sure that this phenomenon will also cause climate change in additional to natural disasters.