Natural concrete keeps lid on Italian volcano
Scientists explain how ground rose 2 meters without bursting
![concrete](https://i0.wp.com/www.sciencenews.org/wp-content/uploads/2015/07/ts_italianconcrete_free.jpg?fit=860%2C460&ssl=1)
SET IN CONCRETE Naturally occurring concretelike rock allowed the ground around the volcanic Campi Flegrei caldera in Italy to rise a couple meters without bursting, new research finds. Cracks in the nearby rock (shown) vent gas and heat from deep underground.
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