Hong Kong has announced the discovery of a scenic 140 million year old supervolcano southeast of the islands, reports the Wall Street Journal.

The original base of the volcano was huge, and would have measured about 11 miles in diameter. In an eruption, it would have been able to spew 312 cubic miles of ash – enough to blanket all of Hong Kong, according to Denise Tang of the government’s civil engineering & development department. Government scientists believe that downtown Hong Kong sits above remnants of the supervolcano. It is one of the first to be discovered in southeastern China.

Hexagonical rock columns and small islands are the beautiful remnants and only evidence that the supervolcano existed. There are 50 supervolcanos believed to have existed around the world, according to the Journal.