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Pyroclastic density currents at Etna volcano, Italy: The 11 February 2014 case study

Fig. 02
Fig. 2. Views of the upper eastern slope of Etna preceding the 11 February 2014 PDC (a, b, and c are frames from the EMCT camera showing the January and February 2014 lava flows descending from the NSEC upper eastern slope). a) Lava flow from the effusive vent (yellow arrow) that opened on 22 January, and coeval Strombolian activity at the summit of the NSEC (view on 26 January). b) Opening of new effusive vents (yellow arrow) on 10 February by 05:41 GMT upslope of the 22 January vent. c) Opening of a new effusive vent (yellow arrow) at around 04:16 GMT on 11 February, approximately 100 m S of the 22 January vent (Fig. 2a), and coeval extension of the 10 February vent area. The white arrow indicates another lava flow already active on the E flank of the NSEC. d) Photo taken at 00:50 GMT on 11 February from M. Fontane (~7 km from the NSEC; photo by Frank Berger). A field of glowing/incandescent fractures (yellow rectangular area) is visible around the 10 February effusive vent (c). The 11 February PDC originated between this area and the lower effusive vents. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)

Andronico D., A. Di Roberto, E. De Benia, B. Behncke, A. Bertagnini, P. Del Carlo, M. Pompilio (2018).
Journal of Volcanology and Geothermal Research, 357, 92–105,


On 11 February 2014, a considerable volume (0.82 to 1.29 × 106 m3) of unstable and hot rocks detached from the lower–eastern flank of the New Southeast Crater (NSEC) at Mt. Etna, producing a pyroclastic density current (PDC). This event was by far the most extensive ever recorded at Mt. Etna since 1999 and has attracted the attention of the scientific community and civil protection to this type of volcanic phenomena, usually occurring without any clear volcanological precursor and especially toward the mechanisms which led to the crater collapse, the PDC flow dynamics and the related volcanic hazard. We present here the results of the investigation carried out on the 11 February 2014 collapse and PDC events; data were obtained through a multidisciplinary approach which includes the analysis of photograph, images from visible and thermal surveillance cameras, and the detailed stratigraphic, textural and petrographic investigations of the PDC deposits. Results suggest that the collapse and consequent PDC was the result of a progressive thermal and mechanical weakening of the cone by repeated surges of magma passing through it during the eruptive activity prior to the 11 February 2014 events, as well as pervasive heating and corrosion by volcanic gas. The collapse of the lower portion of the NSEC was followed by the formation of a relatively hot (up to 750 °C) dense flow which travelled about 2.3 km from the source, stopping shortly after the break of the slope and emplacing the main body of the deposit which ranges between 0.39 and 0.92 × 106 m3. This flow was accompanied a relatively hot cloud of fine ash that dispersed over a wider area.
The results presented may contribute to the understanding of this very complex type of volcanic phenomena at Mt. Etna and in similar volcanic settings of the world. In addition, results will lay the basis for the modeling of crater collapse and relative PDC events and consequently for the planning of hazard assessment strategies aimed at reducing the potential risks to scientists and tens of thousands of tourists visiting Etna’s summit areas every year.