An asteroid slamming into the earth is another theory. But scientists have stated that there are no known asteroids heading for earth in that time frame. An asteroid will pass “close” to the earth, but the definition of close, in this case, is about 18 times the distance from earth to the moon. While that’s close in astronomical terms, it’s not close enough to cause us any problems.
Another theory is a massive solar flare causing a geomagnetic reversal event. The effect that this reversal will have is changing the polarity of the earth’s poles, therefore causing massive natural disasters.
Many sites have appeared on the internet offering theories, advice and info on the phenomenon that is 2012, but only one has masses of information on the subject. This site features reports on the truth about the various disasters that will strike earth, including a full 360 degree look at 2012. The site offers a fascinating insight, whether you are an expert or are just finding out about this subject for the first time.