Granular disruption during explosive volcanic eruptions


Explosive volcanic eruptions are among the most energetic events on Earth. The hazard to surrounding populations and aviation is controlled by the concentration and size of particles that exit the volcanic vent. The size distribution of volcanic particles is thought to be determined by the initial fragmentation process1,2,3,4, where bubbly magmatic mixtures transition to gas-particle flows. Here we show that collisional processes in the volcanic conduit after initial fragmentation can change the grain-size distribution of particles that leave the volcanic vent. We use experimental analysis of the breakup of natural volcanic rocks during collisions, as well as numerical simulations, to estimate the probability that particles pass through the volcanic conduit and survive intact. We find that breakup in the conduit is strongly controlled by the initial particle size and the location of the initial fragmentation: particles that measure more than 1 cm in diameter and those fragmented at great depths break up most frequently. Abundant large pumice clasts in volcanic deposits therefore imply shallow fragmentation that may be transient. In contrast, fragmentation events at depth will lead to enhanced ash production and greater atmospheric loading of long-residence, fine-grained ash.

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Figure 1: Summary of pumice collision and breakup experiments.
Figure 2: Analytical model results.
Figure 3: Numerical simulation of particle breakup in the conduit.
Figure 4: Lagrangian analysis of disruptive collisions.


  1. 1

    Wohletz, K. H., Sheridan, M. F. & Brown, W. K. Particle-size distributions and the sequential fragmentation-theory applied to volcanic ash. J. Geophys. Res. 94, 15703–15721 (1989).

  2. 2

    Buttner, R., Dellino, P., Raue, H., Sonder, I. & Zimanowkski, B. Stress-induced brittle fragmentation of magmatic melts: Theory and experiments. J. Geophys. Res. 111, B08204 (2006).

  3. 3

    Heiken, G. Morphology and petrography of volcanic ashes. Geol. Soc. Am. Bull. 83, 1961–1988 (1972).

  4. 4

    Kueppers, U., Scheu, B., Spieler, O. & Dingwell, D. B. Fragmentation efficiency of explosive volcanic eruptions: A study of experimentally generated pyroclasts. J. Volcanol. Geotherm. Res. 153, 125–135 (2006).

  5. 5

    Zhang, Y. X. A criteria for the fragmentation of bubbly magma based on brittle failure theory. Nature 402, 648–650 (1999).

  6. 6

    Papale, P. Strain-induced magma fragmentation in explosive eruptions. Nature 397, 425–428 (1999).

  7. 7

    Dingwell, D. B. Volcaninc dilemma: Flow or blow? Science 273, 1054–1055 (1996).

  8. 8

    Sparks, R. S. J. The dynamics of bubble deformation and growth in mamgas: A review and analysis. J. Volcanol. Geotherm. Res. 3, 1–37 (1978).

  9. 9

    Papale, P. Dynamics of magma flow in volcanic conduits with variable fragmentation efficiency and nonequilibrium pumice degassing. J. Geophys. Res. 106, 11043065–1111065 (2001).

  10. 10

    Dufek, J. & Manga, M. In situ production of ash in pyroclastic flows. J. Geophys. Res. 113, B09207 (2008).

  11. 11

    Schwarzkopf, L. M., Spieler, O., Scheu, B. & Dingwell, D. B. Fall-experiments on Merapi basaltic andesite and constraints on the generation of pyroclastic surges. eEarth 2, 1–5 (2007).

  12. 12

    Walker, G. P. L. Generation and dispersal of fine ash and dust by volcanic eruptions. J. Volcanol. Geotherm. Res. 11, 81–92 (1981).

  13. 13

    Setoh, M. et al. High- and low-velocity impact experiments on porous sintered glass bead targets of different compressive strengths: Outcome sensitivity and scaling. Icarus 205, 702–711 (2010).

  14. 14

    Evans, J. R., Huntoon, J. E., Rose, W. I., Varley, N. R. & Stevenson, J. A. Particle sizes of andesitic ash fallout from vertical eruptions and co-pyroclastic flow clouds, Volcan de Colima, Mexico. Geology 37, 935–938 (2009).

  15. 15

    Manga, M., Patel, A. & Dufek, J. Rounding of pumice clasts during transport: Field measurements and laboratory studies. Bull. Volcanol. 73, 321–333 (2011).

  16. 16

    Taddeucci, J. & Palladino, D. M. Particle size-density relationships in pyroclastic deposits: Inferences for emplacement processes. Bull. Volcanol. 64, 273–284 (2002).

  17. 17

    Dartevelle, S. & Valentine, G. A. Transient multiphase processes during the explosive eruption of basalt through a geothermal borehole (Namafjall, Iceland, 1977) and implications for natural volcanic flows. Earth Planet. Sci. Lett. 262, 363–384 (2007).

  18. 18

    Kaminski, E. & Jaupart, C. The size distribution of pyroclasts and the fragmentation sequence in explosive volcanic eruptions. J. Geophys. Res. 103, 29759–29779 (1998).

  19. 19

    Papale, P. Dynamics of magma flow in volcanic conduits with variable fragmentation efficiency and nonequilibrium pumice degassing. J. Geophys. Res. 106, 11043–11065 (2001).

  20. 20

    Dobran, F. Nonequilibrium flow in volcanic conduits and application to the eruptions of Mt. St. Helens on May 18, 1980, and Vesuvius in AD 79. J. Volcanol. Geotherm. Res. 49, 285–311 (1992).

  21. 21

    Dufek, J. D. & Bergantz, G. W. Transient two-dimensional dynamics in the upper conduit of a rhyolitic eruption: A comparison of the closure models for the granular stress. J. Volcanol. Geotherm. Res. 143, 113–132 (2005).

  22. 22

    Syamlal, M., Rogers, W. & O’Brien, T. J. MFIX Theory Guide Technical Note, 1–49 (US Department of Energy, Morgantown, WV, 1993).

  23. 23

    Dufek, J., Wexler, J. & Manga, M. Transport capacity of pyroclastic density currents: Experiments and models of substrate-flow interaction. J. Geophys. Res. 114, B11203 (2009).

  24. 24

    Legros, F. & Kelfoun, K. Sustained blasts during large volcanic eruptions. Geology 28, 895–898 (2000).

  25. 25

    Neri, A., Di Muro, A. & Rosi, M. Mass partition during collapsing and transitional columns by using numerical simulations. J. Volcanol. Geotherm. Res. 115, 1–18 (2002).

  26. 26

    Dartevelle, S., Rose, W. I., Stix, J., Kelfoun, K. & Vallance, J. W. Numerical modeling of geophysical granular flows: 2. Computer simulations of plinian clouds and pyroclastic flows and surges. Geochem. Geophys. Geosyst. 5, 1–36 (2004).

  27. 27

    Cagnoli, B. & Manga, M. Granular mass flows and Coulomb’s friction in shear cell experiments: Implications for geophysical flows. J. Geophys. Res. 109, F04005 (2004).

  28. 28

    Low, T. B. & List, R. Collision, coalescence and breakup of raindrops. Part I: Experimentally established coalescence efficiencies and fragment size distributions in breakup. J. Atmos. Sci. 39, 1591–1606 (1982).

  29. 29

    Telling, J. & Dufek, J. An experimental evaluation of ash aggregation in explosive volcanic eruptions. J. Volcanol. Geotherm. Res. 209–210, 1–8 (2012).

  30. 30

    Gault, D. E. & Wedekind, J. A. The destruction of tectites my micrometeoroid impact. J. Geophys. Res. 74, 6780–6794 (1969).

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This work was supported by NSF grants 0809321 (J.D.) and 0809564 (M.M.). We thank K. Russell for comments on this manuscript.

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J.D. developed the analysis and numerical model and A.P. and M.M. carried out most of the experiments. All authors contributed to the ideas presented in the manuscript.

Correspondence to Josef Dufek.

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The authors declare no competing financial interests.

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Dufek, J., Manga, M. & Patel, A. Granular disruption during explosive volcanic eruptions. Nature Geosci 5, 561–564 (2012).

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