Explosive volcanism may not be an inevitable consequence of magma fragmentation


The fragmentation of magma, containing abundant gas bubbles, is thought to be the defining characteristic of explosive eruptions1,2,3. When viscous stresses associated with the growth of bubbles and the flow of the ascending magma exceed the strength of the melt2,4,5,6, the magma breaks into disconnected fragments suspended within an expanding gas phase. Although repeated effusive and explosive eruptions for individual volcanoes are common7,8, the dynamics governing the transition between explosive and effusive eruptions remain unclear. Magmas for both types of eruptions originate from sources with similar volatile content, yet effusive lavas erupt considerably more degassed than their explosive counterparts7,8. One mechanism for degassing during magma ascent, consistent with observations, is the generation of intermittent permeable fracture networks generated by non-explosive fragmentation near the conduit walls9,10,11. Here we show that such fragmentation can occur by viscous shear in both effusive and explosive eruptions. Moreover, we suggest that such fragmentation may be important for magma degassing and the inhibition of explosive behaviour. This implies that, contrary to conventional views, explosive volcanism is not an inevitable consequence of magma fragmentation.

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Figure 1: Deformation textures of annealed fragments in obsidian from Big Glass Mountain, California.
Figure 2: Evolution of a typical model simulation.
Figure 3: Model results and predicted occurrence of shear-induced fragmentation.


  1. 1

    Eichelberger, J. C. Silicic volcanism: ascent of viscous magmas from crustal reservoirs. Annu. Rev. Earth Planet. Sci. 23, 41–63 (1995)

    ADS  CAS  Article  Google Scholar 

  2. 2

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

    ADS  CAS  Article  Google Scholar 

  3. 3

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

    ADS  CAS  Article  Google Scholar 

  4. 4

    Dingwell, D. B. & Webb, S. L. Structural relaxation in silicate melts and non-Newtonian melt rheology in geologic processes. Phys. Chem. Miner. 16, 508–516 (1989)

    ADS  CAS  Article  Google Scholar 

  5. 5

    Webb, S. L. & Dingwell, D. B. The onset of non-Newtonian rheology of silcate melts. Phys. Chem. Miner. 17, 125–132 (1990)

    ADS  CAS  Article  Google Scholar 

  6. 6

    Webb, S. L. & Dingwell, D. B. Non-Newtonian rheology of igneous melts at high stresses and strain rates: experimental results for rhyolite, andesite, basalt, and nephelinite. J. Geophys. Res. 95, 15695–15701 (1990)

    ADS  Article  Google Scholar 

  7. 7

    Newman, S., Epstein, S. & Stolper, E. Water, carbon dioxide and hydrogen isotopes in glasses from the ca. 1340 A.D. eruption of the Mono Craters, California: Constraints on degassing phenomena and initial volatile content. J. Volcanol. Geotherm. Res. 35, 75–96 (1988)

    ADS  CAS  Article  Google Scholar 

  8. 8

    Villemant, B. & Boudon, G. Transition from dome-forming to plinian eruptive styles controlled by H2O and Cl degassing. Nature 392, 65–69 (1998)

    ADS  CAS  Article  Google Scholar 

  9. 9

    Polacci, M., Papale, P. & Rosi, M. Textural heterogeneities in pumices from the climactic eruption of Mount Pinatubo, 15 June 1991, and implications for magma ascent dynamics. Bull. Volcanol. 63, 83–97 (2001)

    ADS  Article  Google Scholar 

  10. 10

    Tuffen, H., Dingwell, D. B. & Pinkerton, H. Repeated fracture and healing of silicic magma generates flow banding and earthquakes? Geology 31, 1089–1092 (2003)

    ADS  Article  Google Scholar 

  11. 11

    Stasiuk, M. V. et al. Degassing during magma ascent in the Mule Creek vent (USA). Bull. Volcanol. 58, 117–130 (1996)

    ADS  Article  Google Scholar 

  12. 12

    Goto, A. A new model for volcanic earthquake at Unzen Volcano: Melt rupture model. Geophys. Res. Lett. 26, 2541–2544 (1999)

    ADS  Article  Google Scholar 

  13. 13

    Mastin, L. G. Insights into volcanic conduit flow from an open-source numerical model. Geochem. Geophys. Geosyst. 3, doi:10.1029/2001GC000192 (2002)

  14. 14

    Proussevitch, A. A., Sahagian, D. L. & Anderson, A. T. Dynamics of diffusive bubble growth in magmas: Isothermal case. J. Geophys. Res. 3, 22283–22307 (1993)

    ADS  Article  Google Scholar 

  15. 15

    Lensky, N. G., Lyakhovsky, V. & Navon, O. Radial variations of melt viscosity around growing bubbles and gas overpressure in vesiculating magmas. Earth Planet. Sci. Lett. 186, 1–6 (2001)

    ADS  CAS  Article  Google Scholar 

  16. 16

    Rust, A. C. & Manga, M. Effects of bubble deformation on the viscosity of dilute suspensions. J. Non-Newtonian Fluid Mech. 104, 53–63 (2002)

    CAS  Article  Google Scholar 

  17. 17

    Pal, R. Rheological behavior of bubble-bearing magmas. Earth Planet. Sci. Lett. 207, 165–179 (2003)

    ADS  CAS  Article  Google Scholar 

  18. 18

    Llewellin, E. W., Mader, H. M. & Wilson, S. D. R. The constitutive equation and flow dynamics of bubbly magmas. Geophys. Res. Lett. 29, doi:10.1029/2002GL015697 (2002)

  19. 19

    Simmons, J. H., Mohr, R. K. & Montrose, C. J. Non-Newtonian viscous flow in glass. J. Appl. Phys. 53, 4075–4080 (1982)

    ADS  CAS  Article  Google Scholar 

  20. 20

    Hess, K.-U. & Dingwell, D. B. Viscosities of hydrous leucogranitic melts: A non-Arrhenian model. Am. Mineral. 81, 1297–1300 (1996)

    CAS  Google Scholar 

  21. 21

    Manga, M. & Loewenberg, M. Viscosity of magmas containing highly deformable bubbles. J. Volcanol. Geotherm. Res. 105, 19–24 (2001)

    ADS  CAS  Article  Google Scholar 

  22. 22

    Pyle, D. M. in Encyclopedia of Volcanoes (eds Sigurdsson, H., Houghton, B. F., McNutt, S. R., Rymer, H. & Stix, J.) 263–269 (Academic, San Diego, 2000)

    Google Scholar 

  23. 23

    Jaupart, C. & Allegre, C. J. Gas content, eruption rate and instabilities of eruption regime in silicic volcanoes. Earth Planet. Sci. Lett. 102, 413–429 (1991)

    ADS  Article  Google Scholar 

  24. 24

    Boudon, G., Villemant, B., Komorowski, J.-C., Ildefonse, P. & Semet, M. P. The hydrothermal system at Soufriere Hills volcano, Montserrat (West Indies): characterization and role in the on-going eruption. Geophys. Res. Lett. 25, 3693–3696 (1998)

    ADS  CAS  Article  Google Scholar 

  25. 25

    Blower, J. D. Factors controlling porosity-permeability relationships in magma. Bull. Volcanol. 63, 497–504 (2001)

    ADS  Article  Google Scholar 

  26. 26

    Klug, C. & Cashman, K. V. Permeability development in vesiculating magmas: implications for fragmentation. Bull. Volcanol. 58, 87–100 (1996)

    ADS  Article  Google Scholar 

  27. 27

    Klug, C., Cashman, K. V. & Bacon, C. R. Structure and physical characteristics of pumice from the climactic eruption of Mount Mazama (Crater Lake), Oregon. Bull. Volcanol. 64, 486–501 (2002)

    ADS  Article  Google Scholar 

  28. 28

    Gottsmann, J. & Dingwell, D. B. The thermal history of a spatter-fed lava flow: the 8-ka pantellerite flow of Mayor Island, New Zealand. Bull. Volcanol. 64, 410–422 (2002)

    ADS  Article  Google Scholar 

  29. 29

    Smith, J. V. Ductile-brittle transition structures in the basal shear zone of a rhyolite lava flow, eastern Australia. J. Volcanol. Geotherm. Res. 72, 217–223 (1996)

    ADS  CAS  Article  Google Scholar 

  30. 30

    Martel, C., Dingwell, D. B., Spieler, O., Pichavant, M. & Wilke, M. Experimental fragmentation of crystal- and vesicle-bearing melts. Bull. Volcanol. 63, 398–405 (2001)

    ADS  Article  Google Scholar 

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We thank P. Papale and D. L. Sahagian for comments on the previous versions of the manuscript, and K. V. Cashman, A. Rust, and A. M. Jellinek for comments on earlier versions. This work was supported by the National Science Foundation and the Sloan Foundation.

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Correspondence to Helge M. Gonnermann.

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Gonnermann, H., Manga, M. Explosive volcanism may not be an inevitable consequence of magma fragmentation. Nature 426, 432–435 (2003). https://doi.org/10.1038/nature02138

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