SICILY, Italy – Italy’s Mount Etna volcano violently erupted on Monday, sending plumes of toxic ash and smoke billowing into the sky as people on the mountain ran for safety to escape the danger.

A lava flow was spotted by satellites winding down the flanks of Mount Etna during an explosive outburst on June 2, which also released a large pyroclastic flow in the opposite direction. | Credit ...

Pyroclastic density current (PDC): A turbulent, high-density flow composed of volcanic ash, lapilli and gases that descends rapidly along a volcano’s slope following an eruption.

Pyroclastic density currents (PDCs) represent some of the most formidable and complex volcanic phenomena, characterised by a turbulent mixture of solid particles and gases that surge down slopes at ...