Upward migration of Vesuvius magma chamber over the past 20,000 years

• Published in: Nature (London) 2008-09, Vol.455 (7210), p.216-219
• Main Authors: Scaillet, B., Pichavant, M., Cioni, R.
• Format: Article
• Language: English
• Subjects: Calderas; Crystalline rocks; Earth sciences; Earth, ocean, space; Epoxy resins; Equilibrium; Exact sciences and technology; Experiments; Feeding rates; Humanities and Social Sciences; Igneous and metamorphic rocks petrology, volcanic processes, magmas; letter; Magma; Mineralogy; multidisciplinary; Ponding; Pressure vessels; Reservoirs; Scanning electron microscopy; Science; Science (multidisciplinary); Volcanic eruptions; Volcanoes
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/nature07232

Vesuvius raises the bar Many magma outbreaks have occurred since Vesuvius left its mark in history in AD 79 by destroying Pompeii and Herculaneum, most recently in 1944. A new eruption could threaten more than 700,000 people in the Bay of Naples, hence the importance of attempts to forecast the eruptive activity of Vesuvius. The depth of the magma reservoir is one of the main parameters controlling magma properties and eruptive style. It had been assumed that the reservoirs that have fed the eruptions during the past 20,000 years have remained roughly in the same place. Yet detailed reconstructions of magma storage conditions based on analysis of material from four main explosive events at Vesuvius show that they have migrated upwards by about 9-11 km between the Pomici di Base event, about 18,500 years ago, and the 1944 eruption. This reservoir migration, and the possible influence on magma feeding rates, should therefore be considered when defining expected eruptive scenarios at Vesuvius. Experimental phase equilibria carried out on material from four main explosive events at Vesuvius are used to show that the reservoirs that fed the eruptive activity migrated from 7–8 km to 3–4 km depth between the 79 AD (Pompei) and 472 AD (Pollena) events. If data from the 18.5 kyr-old Pomici di Base event and the 1944 Vesuvius eruption are included, the total upward migration of the reservoir amounts up to 9–11 km. Reservoir migration, and the possible influence on feeding rates, should accordingly be integrated into the parameters used for defining expected eruptive scenarios at Vesuvius. Forecasting future eruptions of Vesuvius is an important challenge for volcanologists, as its reawakening could threaten the lives of 700,000 people living near the volcano 1 , 2 . Critical to the evaluation of hazards associated with the next eruption is the estimation of the depth of the magma reservoir, one of the main parameters controlling magma properties and eruptive style. Petrological studies have indicated that during past activity, magma chambers were at depths between 3 and 16 km (refs 3–7 ). Geophysical surveys have imaged some levels of seismic attenuation, the shallowest of which lies at 8–9 km depth 8 , and these have been tentatively interpreted as levels of preferential magma accumulation. By using experimental phase equilibria, carried out on material from four main explosive events at Vesuvius, we show here that the reservoirs that fed the eruptive activity migr