Lava spewed from the Voragine crater on Mount Etna on Thursday, July 4, after three weeks of gradually increasing Strombolian activity.This footage by Giuseppe Tonzuso shows the crater spurting lava.Strombolian activity is a relatively low-level volcanic eruption, during which a modest amount of energy is released, according to the National Institute of Geophysics and Volcanology. Credit: Giuseppe Tonzuso via Storyful