How the list is made

Every ten minutes we check the volcanic ash warnings that aviation authorities issue around the world, the alert levels of the US Geological Survey and the weekly volcanic activity report of the Smithsonian Institution and USGS. A volcano is marked as erupting while an ash warning for it is in force; volcanoes with an alert or reports of activity in the last three weeks come next.

An eruption is not always visible: clouds, night or the wind can hide the ash plume, and some volcanoes erupt in short bursts. If the picture is calm, come back in a while - the most active volcanoes, such as Sakurajima, Semeru or Fuego, often erupt several times a day.