Bulletin of Volcanology

, Volume 74, Issue 8, pp 1849–1858 | Cite as

Bombs behaving badly: unexpected trajectories and cooling of volcanic projectiles

  • Loÿc VanderkluysenEmail author
  • Andrew J. L. Harris
  • Karim Kelfoun
  • Costanza Bonadonna
  • Maurizio Ripepe
Research Article


We collected thermal infrared video of two explosive eruptions at Stromboli in June 2008 and manually traced the trajectories of 95 particles launched during two eruptions. We found that 10–15 % of the analyzed trajectories deviated from predicted curves due to collisions, causing one particle to travel horizontally more than twice as far as expected. Furthermore, we observed an oscillatory cooling behavior for the airborne pyroclasts, with a median period of 0.46 s. Measured cooling was typically much faster than model-predicted cooling with discrepancies of up to 40 % between measured cooling and theoretical modeling. We interpret the measured cooling curves as resulting from the spinning and twisting and tearing of particles during travel: the periodic re-exposing of the hotter core of the pyroclasts to the atmosphere may cause the observed oscillations, and the spinning may accelerate cooling by enhancing convective heat transfer. Current volcanic trajectory and cooling models do not account for projectile collisions, spinning, or tearing and can thus severely underestimate the maximum landing distance and cooling rates of large pyroclasts.


Strombolian eruption Stromboli Thermal Ballistic trajectory Bomb Pyroclast cooling 



We acknowledge J. Dehn, L. Colò, T. Lopez, and K. Horton for their help in the field. M. May processed the June 3, 2008 explosion trajectories. We thank the associate editor and two anonymous reviewers for their comments, which greatly improved the manuscript, and H. Wright, M. Alatorre and M. James for their review of an earlier version of the article. This is SOEST contribution 8674 and HIGP 1933. This work was funded by the US National Science Foundation grant EAR07-38106. AH was supported by la Région Auvergne.

Supplementary material

Electronic supplementary material 1

Thermal video sequence of an explosive eruption at Stromboli volcano viewed from Portella di Ginostra on June 3 at 11:11:02 UTC. Frame rate, 6 Hz. (AVI 8970 kb)

Electronic supplementary material 2

Thermal video sequence of an explosive eruption at Stromboli Volcano viewed from Portella di Ginostra on June 5 at 13:10:59 UTC. Frame rate, 6 Hz. (AVI 10245 kb)

Electronic supplementary material 3

Thermal video sequence of an explosive eruption at Stromboli Volcano viewed from the Pizzo sopra la Fossa on June 5 at 13:10:59 UTC. Frame rate, 10 Hz. (AVI 21781 kb)


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Copyright information

© Springer-Verlag 2012

Authors and Affiliations

  • Loÿc Vanderkluysen
    • 1
    • 5
    Email author
  • Andrew J. L. Harris
    • 2
  • Karim Kelfoun
    • 2
  • Costanza Bonadonna
    • 3
  • Maurizio Ripepe
    • 4
  1. 1.Hawai‘i Institute of Geophysics and Planetology, School of Ocean and Earth Science and TechnologyUniversity of Hawai‘iHonoluluUSA
  2. 2.Laboratoire Magmas et VolcansUniversité Blaise PascalClermont-FerrandFrance
  3. 3.Section des Sciences de la Terre et de l’EnvironnementUniversité de GenèveGenevaSwitzerland
  4. 4.Dipartimento di Scienze della TerraUniversità degli Studi di FirenzeFlorenceItaly
  5. 5.ASU School of Earth and Space ExplorationTempeUSA

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