Visit Fourteen Reason Why The Earth is Going to End on December 21, 2012 to know all the predictions and prophecies 

Super volcanoes are no ordinary volcanoes. They are substantially larger than the common volcano and produce the biggest and most deadly eruptions on earth. Yellowstone Volcano is one of the biggest and most realistic of the 2012 predictions. Scientists will tell you today that Yellowstone is overdue for a volcanic eruption, thus leading to the theory that 2012 could be that date. An eruption from this super volcano could be catastrophic, as it is estimated to be 1,000′s of times more powerful than a regular volcano The explosion will fill the atmosphere with ash, blocking the sun and plunging the Earth into a frozen winter that could last up to 15,000 years. The pressure under the Yellowstone is building steadily, and geologists have set 2012 as a likely date for the big bang.

Will world really end on December 21,2012? Many predictions!!
What causes super volcano? What would be the consequences? Did it happen in the past? Many more questions. Visit Cause and effect of Super Volcanoes  to learn more.You may also visit: What are super volcanoes?