Geol. Mag. 147 (3 ), 2010, pp. 391–415. c  Cambridge University Press 2009 391 doi:10.1017/S0016756809990495 The 1944 eruption of Vesuvius, Italy: combining contemporary accounts and field studies for a new volcanological reconstruction PAUL D. COLE ∗ &CLAUDIO SCARPATI † ∗ Department of Geography, Environment and Disaster Management, Coventry University, Priory Street, Coventry CV1 5FB, UK †Dipartimento Scienze Della Terra, Universit` a di Napoli Federico II, Largo S. Marcellino, 10, 80138 Napoli, Italy (Received 15 June 2009; accepted 14 July 2009; First published online 11 November 2009) Abstract – We integrate the different contemporary sources together with new field data on the pyroclastic deposits to make a new volcanological reconstruction of the explosive phases of the 1944 Vesuvius eruption. We adopt the four successive phases of the eruption first defined by Imb` o (1945), who made the most detailed contemporary description of the eruption: Phase 1 – effusive, Phase 2 – lava fountains, Phase 3 – mixed explosions and Phase 4 – seismic-explosive. Phase 1 consisted of four days of effusive activity. Phase 2 generated eight successive lava fountains which formed agglutinated spatter in a restricted area around the crater. At distances of > 1 km from the crater, reverse graded, well-sorted, scoria lapilli with up to 94 wt % juvenile material and calculations indicate a volume of 8.2 × 10 6 m 3 DRE (Dense Rock Equivalent) for Phase 2. A short pause in scoria fallout was observed that coincides with the transition between Phases 2 and 3 of the eruption. On the crater rim there is clear evidence for the different phases, owing to the stratification of the deposits; however, away from the crater, stratigraphic breaks suggesting any discontinuity in the eruptive activity are absent. The beginning of Phase 3 is marked by the appearance of abundant dense scoria fragments, coincident with the coarsest part of the lapilli. High-density scoria forms 10 wt % of juvenile material in Phase 2, increasing to 45 % in the upper part of Phase 3. Isopach maps derived from field measurements indicate a mean volume of 40.2 × 10 6 m 3 DRE for Phase 3. Distal ash, mainly formed during Phase 3, was dispersed to the SE as far as Albania, and calculations yield a volume of 102 × 10 6 m 3 DRE. Intermittent activity associated with Phase 4 generated ash-rich plumes dispersed towards the SW and contemporary thickness descriptions yield a bulk volume of 4.2 × 10 6 m 3 (2.5 × 10 6 m 3 DRE). Small pyroclastic density currents (PDCs) were observed during Phases 3 and 4. The deposits (200 m from the crater rim) of these currents have been identified on the flanks of the cone. Thin, massive and poorly sorted ash layers, that occur up to 2.5 km from the crater rim, are interpreted to represent the distal facies of these PDCs. Mass discharge rate (MDR) estimates for the paroxysmal phase (end of Phase 2 and start of Phase 3) of this event are around 3.5 × 10 6 kg/s, however, this increases to > 10 7 kg/s if the mass of distal ash is taken into account. Column height estimates from fallout isopleths associated with the eruption’s paroxysmal phase are > 10 km. Based on the contemporaneous chronicles, we were able to define the type and extent of damage associated with the different styles (or temporal phases) of the eruption. Our calculations demonstrate that the present-day population at risk has doubled compared to 1944. The contemporaneous (and also subsequent) scientific literature underestimated the magnitude and intensity of this eruption and very little attention has been dedicated to the damage that occurred. We suggest that this is at least partly related to the extensive destruction of Neapolitan area and the deaths of tens of thousands of civilians related to the Second World War. Keywords: 1944 Vesuvius eruption, contemporary accounts, scoria fallout, subplinian, risk. 1. Introduction Every book or paper written in the last 60 years that describes the eruptive history of Vesuvius deals with its last eruption, which occurred in March 1944, during the liberation of the Neapolitan area by the Anglo-American Allies (e.g. Imb` o, 1945; Santacroce, 1987; Cioni et al. 2008). Most of the volcanological descriptions of the 1944 event were provided by Giuseppe Imb` o, director of the Osser- vatorio Vesuviano, who remained at the Observatory on the slopes of the volcano and vividly described ∗ Author for correspondence: p.cole@coventry.ac.uk and pdcole2@ gmail.com; present address: Montserrat Volcano Observatory, Flemings, Montserrat, West Indies the course of the eruption (Imb` o, 1945, 1949a). He defined the successive phases of the eruption as: ‘effus- ive’, ‘lava fountains’, ‘mixed explosions’ (alternating lava fountains and sustained column) and ‘seismic- explosive’ (discontinuous explosions alternating with earthquakes). Imb` o was a direct witness to those events and consequently his evaluations have been adopted in all the following volcanological literature (e.g. Santacroce, 1987; Marianelli, M´ etrich & Sbrana, 1999; Scandone, Iannone & Mastrolorenzo, 1986; Mastrolorenzo, Munno & Rolandi, 1993; Hazlett et al. 1991; Cubellis & Luongo, 1997; Fulignati et al. 2004). In this paper we make a full volcanological recon- struction of the 1944 eruption of Vesuvius, based on in- formation gathered from many different contemporary