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Volcanic processes

Volcanic processes. Volcanic processes and types. « grey » volcanoes More explosive Andesitic Subductions. « red » volcanoes Less explosive Basaltic Intra-plate. Dynamic types related to magma/water interactions Dynamic types related to dissolved bubbles

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Volcanic processes

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  1. Volcanic processes

  2. Volcanic processes and types « grey » volcanoes More explosive Andesitic Subductions « red » volcanoes Less explosive Basaltic Intra-plate

  3. Dynamic types related to magma/water interactions • Dynamic types related to dissolved bubbles • Dynamic types related to domes growth and collapse • Dynamic types related to lava flows etc. • Destruction of volcanic edifices • Complex edifices

  4. Magma viscosity Figure 4-1. a. Calculated viscosities of anhydrous silicate liquids at one atmosphere pressure, calculated by the method of Bottinga and Weill (1972) by Hess (1989), Origin of Igneous Rocks. Harvard University Press. b.Variation in the viscosity of basalt as it crystallizes (after Murase and McBirney, 1973), Geol. Soc. Amer. Bull., 84, 3563-3592.c. Variation in the viscosity of rhyolite at 1000oC with increasing H2O content (after Shaw, 1965, Amer. J. Sci., 263, 120-153).

  5. Mount Saint-Helens:The post-18 May dome

  6. Figure 4-7. Schematic cross section through a lava dome.

  7. Secondary ash fall (+local surges)

  8. Dome growth and collapse • Cortex of the dome « chills », interior still hot • Steep slopes, local collapse • Breccias • Pyroclastic flows: « block and ash flow » • Dense flow, rich in blocks • Smaller scale than plinian!!

  9. Montagne-Pelée, Martinique(lesser Antilles)

  10. Saint-Pierre, before

  11. Saint-Pierre, after

  12. Volcanic processes and types « grey » volcanoes More explosive Andesitic Subductions « red » volcanoes Less explosive Basaltic Intra-plate

  13. Dynamic types related to magma/water interactions • Dynamic types related to dissolved bubbles • Dynamic types related to domes growth and collapse • Dynamic types related to lava flows etc. • Destruction of volcanic edifices • Complex edifices

  14. Lava lakes

  15. Eruptive fissures

  16. Bubbles

  17. Scenic volcanoes! Stromboli (Italy)

  18. Scoria cones

  19. Piton de la Fournaise (Réunion, Indian Ocean)

  20. Cones groupe in Réunion

  21. Puy de Pariou (France) (note also the pelean dome of Puy de Dome at the back)

  22. Scoria cones

  23. Disrupted cones

  24. Cones and lava flows

  25. Etna (Italy)

  26. Strange things lava flows do…

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