The fineness of the ash in this case is unusual, says Thorvaldur Thordarson, an Icelandic volcanologist.

ECONOMIST: Volcanoes and air travel: Small eruption in Iceland | The

On the northern side of the volcano, participants can watch lava spew out of the Earth from a tented camping site 1.5 kilometers away, which has been deemed safe by a volcanologist.

CNN: Congo's erupting volcano boosts tourism

Volcanologist Sonia Calvari, of the Institute of Geophysics and Volcanology in Catania (INGV-CT), said rapid advances in technology enable experts to use a wide range of methods to continually map and monitor Etna from a distance.

CNN: Keeping track of Etna's pulse