A significant geological feature of the volcano is the Sciara del Fuoco (Stream of fire), a big horseshoe shaped depression generated in the last 13,000 years by several collapses on the northwestern side of the cone. Two kilometres to the northeast lies Strombolicchio, the volcanic plug remnant of the original volcano. Mt. Stromboli has been in almost continuous eruption for the past 2,000 years. A pattern of eruption is maintained in which explosions occur at the summit craters, with mild to moderate eruptions of incandescent volcanic bombs, at intervals ranging from minutes to hours. This Strombolian eruption, as it is known, is also observed at other volcanoes worldwide. Eruptions from the summit craters typically result in a few short, mild, but energetic bursts, ranging up to a few hundred metres in height, containing ash, incandescent lava fragments and stone blocks. Mt. Stromboli's activity is almost exclusively explosive, but lava flows do occur at times when volcanic activity is high, an effusive eruption occurred in 2002, the first in 17 years, and again in 2003, 2007, 2013, and 2014.