On the verge of the Sciara

The Sciara del Fuoco, the impressive lateral collapse that dominates the western side of Stromboli volcano (Aeolian Islands, Italy), is a perfect example of what gradient means. With a slope 100%, it allows most of the volcanic products to roll along its flank towards the Tyrrhenian Sea. However, when entire portions of the the Sciara collapse, it cause dangerous tsunamis, as it happened recently in 2002/03 and 2007.