INGV reported that activity at Stromboli had been more intense in the past two weeks with a large explosion on 29 September, short-lived lava overflows of the craters during 3-4 October, and collapses with pyroclastic flows and lava flows on 9 October. At 1524 on 29 September an explosion at vent N2 in Area N (North Crater area) generated an ash plume that rose 300 m above the summit and ejected abundant lava fragments, lapilli, and bombs along the Sciara del Fuoco. Activity during 3-9 October generally consisted of ongoing explosions from three vents in Area N and at least two vents in Area C-S (South-Central Crater area). Low-intensity explosions from the N1 vent (Area N) ejected bombs and lapilli 80-150 m high every 10-20 minutes. Explosions ejecting coarse material, along with sometimes intense spattering, occurred at two N2 vents. Explosions from at least two vents in Area C-S, which were not visible due to the camera views, ejected ash and coarse material less than 150 m above the vent at a rate of 1-6 events per hour. At 1108 on 3 October a fissure opened on the outer flank of N2, within the Sciara del Fuoco, and produced a lava flow that traveled to the coast; the flow was cooling by 1800. At 1107 the next morning, 4 October, lava overflowed the N crater (likely N2) and unconsolidated lava rolled down the upper part of the Sciara del Fuoco.
Activity again intensified on 9 October beginning at 0921 when lava overflowed from an area in the N part of N2 and lava effused from the fissure that had opened on 3 October. At 0922 the rim of N2 collapsed and generated a pyroclastic flow that traveled down the Sciara del Fuoco, reached the sea within 30 seconds, and advanced over the water for a few hundred meters. Immediately afterwards a large amount of lava flowed down the Sciara del Fuoco in two main branches and reached the coast within a few minutes. Lava continued to flow to the coast during the rest of the day. The Dipartimento della Protezione Civile raised the Alert Level to Orange (the second highest level on a four-color scale). Collapses of material in the Sciara del Fuoco continued overnight, possibly due to erosion of the channels from lava flows. By 0919 on 10 October lava flows were only reaching part way down the Sciara del Fuoco, stopping about 400 m from the coast. Lava flows continued to stop part way down the flank during 10-12 October. Frequent collapses of material in the channel eroded by the lava flow and material from the lava flow itself descended to the coast. Spattering from Area N was visible.