Mount Etna, Europe's most active volcano, erupted on Monday, sending a large cloud of smoke and ash high into the air. Catania airport was put on alert, but flights were not stopped, and the ash cloud disappeared by the afternoon. The eruption happened because part of the southeast crater collapsed, which caused hot lava to flow, but it did not put people living nearby in danger. The top of Mount Etna was closed to tourists as a safety measure, but the lava stayed in its natural area. People in nearby towns and villages felt the eruption, and it caused a lot of discussion on social media. Even with this event, Etna is still a popular place for tourists because it is very tall and has a large surface area.