The continuing story of Etna's New Southeast Crater (2012–2014): Evolution and volume calculations based on field surveys and aerophotogrammetry E. De Beni a , B. Behncke a, ⁎, S. Branca a , I. Nicolosi b , R. Carluccio b , F. D'Ajello Caracciolo b , M. Chiappini b a Istituto Nazionale di Geofisica e Vulcanologia-Osservatorio Etneo, Piazza Roma 2, Catania Italy b Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata 605, 00143 Roma, Italy abstract article info Article history: Received 15 April 2015 Accepted 16 July 2015 Available online 26 July 2015 Keywords: Etna Summit eruptions Pyroclastic cone Volcano growth Aerophotogrammetry Lava and tephra volume During the years 2013–2014, the New Southeast Crater (NSEC) at the summit of Mount Etna produced frequent episodes of lava fountaining (paroxysms), and its cone continued to grow at unprecedented rates. Many of the episodes were of rather brief duration and violently explosive, producing mostly pyroclastic material and minor volumes of lava. Other episodes, especially those since mid-December 2013, were characterized by violent Strombolian activity without producing sustained lava fountains and significant amounts of tephra, but emitting more voluminous lava flows. One episode of intense Strombolian and effusive activity that was possibly fed from the NSEC conduit occurred from vents located approximately 1 km north of the crater, on the east flank of the Northeast Crater, in July–August 2014. The evolution of the NSEC cone between 2012 and 2014 was documented by repeated GPS surveys carried out both from a distance and on the cone itself, by the acquisition of comparison photographs, and by two aerophotogrammetric surveys. From these surveys the highest point of the NSEC results to have grown from 190 m (May 2012) to ̴ 215 m (October 2014) above the pre-cone surface reaching an eleva- tion of 3290 m, and its volume more than doubled to ̴ 50.0 ± 6.5 × 10 6 m 3 , representing the 40% of the total (bulk) volume of the volcanic products including pyroclastic fallout erupted in 2011–2014, which is 147.2 × 10 6 m 3 (101.3 × 10 6 m 3 dense-rock equivalent). The whole of the 2011–2014 NSEC activity marks an unusually high fre- quency of rather explosive, tephra-rich eruptive episodes compared to Etna's activity in past decades and centu- ries, although the average magma production rate in this interval is close to the supposed long-term output rate of the volcano. The latest eruptive episodes show a tendency of the NSEC coalescing with the old Southeast Crater cone, which therefore represents a miniature example of a growing compound volcano at the summit of Etna. © 2015 Elsevier B.V. All rights reserved. 1. Introduction Active volcanoes grow in different ways and at different timescales. These range from the geologically instantaneous birth, growth and death of monogenetic features (maars, scoria cones, lava domes) lasting months to years (e.g., Parícutin, Mexico, 1943–1952; Luhr and Simkin, 1993), to the millions-of-years-long construction of large, complex vol- canic edifices such as the Hawaiian and Canary Island volcanoes (Moore and Clague, 1992; Carracedo, 1999) or the Katmai volcanic cluster, Alaska, and Mount Mazama-Crater Lake volcano, Oregon (Bacon and Lanphere, 2006; Hildreth and Fierstein, 2012). For some cases of mono- genetic eruptions the edifice growth rates are well documented, espe- cially for Parícutin (Foshag and González, 1956; Luhr and Simkin, 1993), and the Showa-Shinzan lava dome at Usu volcano, Japan (1943–1944; Minakami et al., 1951). More complex, well-documented examples of new volcanic edifice growth are the Pu'u ‘O’ō cone of Kīlauea, Hawai'i (Wolfe, 1988; Heliker et al., 2003) and the old cone of Etna's Southeast Crater (Behncke et al., 2006). Instead, if lava dome- building eruptions are excluded, the short-term growth of a major volcano does not seem to have been documented in any detail thus far except for Pacaya volcano, Guatemala (Rose et al., 2013). Between January 2011 and April 2012, a series of brief but powerful eruptive episodes (paroxysms) led to the rapid growth of a new cone in the summit area of Mount Etna (Italy) (Behncke et al., 2014). This cone, informally named New Southeast Crater (NSEC), was built up of near- vent pyroclastic fallout and numerous lava flows, mostly by overflows from the crater or nearby vents, but also of rheomorphic (fountain- fed) origin. Rather than a pyroclastic cone, like the cones on the flanks of Etna, it is thus a true – though small – stratovolcano on top of the much larger compound volcano Etna, the only one to our knowledge, whose growth has been documented in detail from its birth onward (Fig. 1). The NSEC resumed its episodic activity after a hiatus of 10 months in February 2013 and produced 19 more paroxysms through early Journal of Volcanology and Geothermal Research 303 (2015) 175–186 ⁎ Corresponding author. E-mail address: boris.behncke@ingv.it (B. Behncke). http://dx.doi.org/10.1016/j.jvolgeores.2015.07.021 0377-0273/© 2015 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Journal of Volcanology and Geothermal Research journal homepage: www.elsevier.com/locate/jvolgeores