Strombolian eruptions are named from the small volcano-island of Stromboli, located between Sicily and Italy. This volcano has been erupting almost constantly for hundreds of years. It erupts irregularly every twenty minutes or so to produce an episodic lightshow that gives rise to its nickname, the "Lighthouse of the Mediterranean".

The term "strombolian" has been used indiscriminately to describe a variety of volcanic eruptions that vary from small volcanic blasts, to kilometer-high eruptive columns. However, true strombolian activity is characterized by short-lived, explosive outbursts of pasty lava ejected a few tens or hundreds of meters into the air. Unlike Hawaiian eruptions, Strombolian eruptions never develop a sustained eruption column. They eject relatively viscous basaltic lava from the throat of the volcano. Build up of the high gas pressures required to fragment this somewhat pasty lava, results in episodic explosions with booming blasts. Although Strombolian eruptions are much noisier than Hawaiian eruptions, they are no more dangerous. As shown in the images above and below, Strombolian explosions eject bomb- and lapilli-sized fragments that travel in parabolic ballistic paths before accumulating around the vent to construct the volcanic edifice. Typically, these eruptions form scoria cones composed of basaltic pryoclasts. However, mafic stratovolcanoes can also exhibit common Strombolian activity, evident for example, at Mt. Eberus in Antarctica and at Stromboli itself.

Pyroclastic particles like Pele's tears, Pele's hair, and reticulite, which are common in Hawaiian eruptions, are not present in Strombolian eruptions. Spatter-fed flows are minor. Instead, Strombolian eruptions are dominated by scoria fragments, which are highly vesiculated clasts of basalt with a cindery appearance. Tephra bombs and lapilli accumulate around the vent to produce well-bedded, and often well-sorted, scoria-fall deposits

In contrast to Hawaiian eruptions, true Strombolian eruptions produce little or no flowing lava. However, during the end stages of scoria-cone formation, it is not unusual for Strombolian activity to wane and give way to the calm extrusion of basaltic lava flows. As a general rule, a'a lava flows appear to be more common than the more fluid pahoehoe types. As the vesiculating lava is de-gased toward the end of the eruption, it may ooze out from under the volcanic edifice to produce a lava flow, or pond in the vent to produce a lava lake. This will only occur if the underlying basalt is fluid enough to flow, which has not proved to be the case at Stromboli itself.

© Dr. Vic Camp, How Volcanoes Work, http://www.geology.sdsu.edu/how_volcanoes_work/ 2004