HR: 13:50h
AN: V33A-02    [Abstracts]
TI: The Size and Frequency of the Largest Explosive Volcanic Eruptions on Earth
AU: Mason, B G
EM: B.Mason@uea.ac.uk
AF: University of East Anglia, School of Environmental Sciences UEA, Norwich, NR4 7TJ United Kingdom
AU: * Pyle, D M
EM: dmp11@cam.ac.uk
AF: University of Cambridge, Department of Earth Sciences Downing Street, Cambridge, CB2 3EQ United Kingdom
AB: An analysis of the size and frequency of the largest known explosive eruptions on Earth reveals 42 known eruptions with erupted masses in excess of 10¹⁵ kg (magnitude 8 or larger) in the past 40 million years. This places the minimum frequency of eruptions of magnitude 8 and larger at ~1.4 Ma^-1, in two pulses over the past 40 Ma. On the basis of the activity of the past 13.5 Ma, there is at least a 75% probability of an eruption of this scale occurring within the next 1 Ma. There is a 1% chance of an eruption of this scale in the next 460 - 7200 years. While the impact of any individual large magnitude eruption would be considerable, the time-averaged impact (i.e. erupted mass × frequency) of the very largest eruptions is small, due to their rarity. The long-term time-averaged erupted mass flux from magnitude 8 and 9 eruptions is one to two orders of magnitude less than for magnitude 7 eruptions, involving between 10¹⁴ and 10¹⁵ kg of magma. Comparison of the energy release by volcanic eruptions with that due to asteroid impacts suggests that on timescales of < 100,000 years, energetic volcanic eruptions are considerably more frequent than impacts of a similar energy yield and destructiveness. This has important implications for our understanding of risk from extreme events.
UR: http://www-volcano.geog.cam.ac.uk/database/
DE: 0370 Volcanic effects (8409)
DE: 8400 VOLCANOLOGY
DE: 8414 Eruption mechanisms
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2005 Joint Assembly