What are these Giant Sinkholes?

Philippines
November 1, 2010 3:56pm CST
Aside from too many calamities the world is undergoing at the moment, the prevalent of giant sinkhole is coming into surface. China was firstly documented to have this, not long ago the appearance of another giant sinkhole in Latin America, in the country of Guatemala and recently in Germany. Where are those giant sinkhole came from? What's going on with our world?
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