Multiphase flow behaviour and hazard prediction of pyroclastic density currents

Abstract

Pyroclastic density currents (PDCs) are dangerous multiphase flows originating from volcanic eruptions. PDCs cause more than a third of volcanic fatalities globally and, therefore, development of robust PDC hazard models is a priority in volcanology and natural hazard science. However, the complexity of gas–particle interactions inside PDCs, as well as their hostile nature, makes quantitative measurements of internal flow properties, and the validation of hazard models, challenging. Within the last decade, major advances from large-scale experiments, field observations and computational and theoretical models have provided new insights into the enigmatic internal structure of PDCs and identified key processes behind their fluid-like motion. Recent developments have also revealed important links between newly recognized processes of mesoscale turbulence and PDC behaviour. In this Review, we consider how recent advances in PDC research close the gaps towards more robust hazard modelling, outline the need to measure the internal properties of natural flows using geophysical methods and identify critical future research challenges. Greater understanding of PDCs will also provide insights into the dynamics of other natural gravity currents and high-energy turbulent multiphase flows, such as debris avalanches and turbidity currents.

Key points

  • We are not yet learning quickly enough about pyroclastic density currents (PDCs) to save lives.

  • Recent advances in experimental and computational studies delineate the concentration boundaries that separate dilute, intermediate and concentrated regimes of PDC transport.

  • Mass and momentum transfer between dilute and concentrated flow regions, and, thus, the evolving transport behaviour, is controlled by the recently identified intermediate regime.

  • Identification of pore-pressure feedbacks in experimental PDCs, combined with multiphase modelling, provide insights into the origin of the high mobility and extremely low effective friction of PDCs.

  • New geophysical methods to probe the internal flow structure are becoming available and will provide data to test existing PDC flow models and drive future research.

  • The advanced understanding of PDCs gained from combining experimental, computational and field approaches must be used to benchmark, validate and advance PDC hazard models.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

Fig. 1: Conceptual models and multiscale spectra of PDCs.
Fig. 2: Approaches to estimate flow velocity, density and temperature from deposit characteristics.
Fig. 3: Delineating concentrated, intermediate and dilute transport regimes in PDCs.
Fig. 4: Concentrated transport regimes of PDCs.
Fig. 5: The dilute turbulent transport regime.
Fig. 6: The intermediate transport regime.
Fig. 7: Application of geophysical observations and modelling to PDC research.

References

  1. 1.

    Dufek, J. The fluid mechanics of pyroclastic density currents. Annu. Rev. Fluid Mech. 48, 459–485 (2016). A review of experimental, theoretical and computational work, with a focus on fluid-dynamic approaches, illustrating advances and current challenges in PDC research.

    Article  Google Scholar 

  2. 2.

    Trolese, M., Cerminara, M., Esposti Ongaro, T. & Giordano, G. The footprint of column collapse regimes on pyroclastic flow temperatures and plume heights. Nat. Commun. 10, 2476 (2019).

    Article  Google Scholar 

  3. 3.

    Clarke, A. B., Voight, B., Neri, A. & Macedonio, G. Transient dynamics of vulcanian explosions and column collapse. Nature 415, 897–901 (2002).

    Article  Google Scholar 

  4. 4.

    Fink, J. H. & Kieffer, S. W. Estimate of pyroclastic flow velocities resulting from explosive decompression of lava domes. Nature 363, 612–615 (1993).

    Article  Google Scholar 

  5. 5.

    Cole, P. D. et al. Pyroclastic flows generated by gravitational instability of the 1996–97 lava dome of Soufriere Hills Volcano, Montserrat. Geophys. Res. Lett. 25, 3425–3428 (1998).

    Article  Google Scholar 

  6. 6.

    Belousov, A., Voight, B. & Belousova, M. Directed blasts and blast-generated pyroclastic density currents: a comparison of the Bezymianny 1956, Mount St Helens 1980, and Soufriere Hills, Montserrat 1997 eruptions and deposits. Bull. Volcanol. 69, 701–740 (2007).

    Article  Google Scholar 

  7. 7.

    Komorowski, J.-C. et al. Paroxysmal dome explosion during the Merapi 2010 eruption: processes and facies relationships of associated high-energy pyroclastic density currents. J. Volcanol. Geotherm. Res. 261, 260–294 (2013). Local topographic features can change the internal structure of PDCs and their deposits, dramatically increasing their runout and causing unexpected decoupling of high-energy currents.

    Article  Google Scholar 

  8. 8.

    Lube, G. et al. Dynamics of surges generated by hydrothermal blasts during the 6 August 2012 Te Maari eruption, Mt. Tongariro, New Zealand. J. Volcanol. Geotherm. Res. 286, 348–366 (2014). Even small-volume, relatively dilute PDCs can severely impact the volcano surroundings and pose serious hazards for residents and tourists.

    Article  Google Scholar 

  9. 9.

    Fujinawa, A., Ban, M., Ohba, T., Kontani, K. & Miura, K. Characterization of low-temperature pyroclastic surges that occurred in the northeastern Japan arc during the late 19th century. J. Volcanol. Geotherm. Res. 178, 113–130 (2008).

    Article  Google Scholar 

  10. 10.

    Kaneko, T., Maeno, F. & Nakada, S. 2014 Mount Ontake eruption: characteristics of the phreatic eruption as inferred from aerial observations. Earth Planets Space 68, 72 (2016).

    Article  Google Scholar 

  11. 11.

    Lube, G., Cronin, S. J. & Procter, J. N. Explaining the extreme mobility of volcanic ice-slurry flows, Ruapehu volcano, New Zealand. Geology 37, 15–18 (2009).

    Article  Google Scholar 

  12. 12.

    Self, S. & Rampino, M. R. The 1883 eruption of Krakatau. Nature 294, 699–704 (1981).

    Article  Google Scholar 

  13. 13.

    Walker, G. P. L., Heming, R. F. & Wilson, C. J. N. Low-aspect ratio ignimbrites. Nature 283, 286–287 (1980).

    Article  Google Scholar 

  14. 14.

    Baxter, P. J. et al. The impacts of pyroclastic surges on buildings at the eruption of the Soufriere Hills volcano, Montserrat. Bull. Volcanol. 67, 292–313 (2005).

    Article  Google Scholar 

  15. 15.

    Neri, A., Esposti Ongaro, T., Voight, B. & Widiwijayanti, C. in Volcanic Hazards, Risks and Disasters (eds Shroder, J. F. & Papale, P.) 109–140 (Elsevier, 2015).

  16. 16.

    Moore, J. G., & Sisson, T. W. in The 1980 Eruptions of Mount St. Helens, Washington (eds Lipman, P. W. & Mullineaux, D. R.) 421–438 (US Geological Survey, 1981).

  17. 17.

    Cronin, S. J. et al. Insights into the October–November 2010 Gunung Merapi eruption (Central Java, Indonesia) from the stratigraphy, volume and characteristics of its pyroclastic deposits. J. Volcanol. Geotherm. Res. 261, 244–259 (2013).

    Article  Google Scholar 

  18. 18.

    Valentine, G. A. Damage to structures by pyroclastic flows and surges, inferred from nuclear weapons effects. J. Volcanol. Geotherm. Res. 87, 117–140 (1998).

    Article  Google Scholar 

  19. 19.

    Clarke, A. B. & Voight, B. Pyroclastic current dynamic pressure from aerodynamics of tree or pole blow-down. J. Volcanol. Geotherm. Res. 100, 395–412 (2000).

    Article  Google Scholar 

  20. 20.

    Jenkins, S. et al. The Merapi 2010 eruption: an interdisciplinary impact assessment methodology for studying pyroclastic density current dynamics. J. Volcanol. Geotherm. Res. 261, 316–329 (2013).

    Article  Google Scholar 

  21. 21.

    Mastrolorenzo, G. et al. Herculaneum victims of Vesuvius in AD 79. Nature 410, 769–770 (2001).

    Article  Google Scholar 

  22. 22.

    Baxter, P. J., Neri, A. & Todesco, M. Physical modelling and human survival in pyroclastic flows. Nat. Hazards 17, 163–176 (1998).

    Article  Google Scholar 

  23. 23.

    Surono et al. The 2010 explosive eruption of Java’s Merapi volcano — A ‘100-year’ event. J. Volcanol. Geotherm. Res. 241–242, 121–135 (2012).

    Article  Google Scholar 

  24. 24.

    Andreastuti, S. et al. Character of community response to volcanic crises at Sinabung and Kelud volcanoes. J. Volcanol. Geotherm. Res. 382, 298–310 (2019).

    Article  Google Scholar 

  25. 25.

    Gunawan, H. et al. Overview of the eruptions of Sinabung Volcano, 2010 and 2013–present and details of the 2013 phreatomagmatic phase. J. Volcanol. Geotherm. Res. 382, 103–119 (2019).

    Article  Google Scholar 

  26. 26.

    Berger, P. Report on Sinabung (Indonesia). Bulletin of the Global Volcanism Network, 42:2. (ed. Venzke, E.) (Smithsonian Institution, 2017).

  27. 27.

    World Bank. Forensic analysis of the conditions of disaster risk in the 2018 Volcano of Fire (Volcán de Fuego) eruption: opportunities for the strengthening of disaster risk management in Guatemala (World Bank Group, 2018).

  28. 28.

    Pallister, J. S. et al. Merapi 2010 eruption — Chronology and extrusion rates monitored with satellite radar and used in eruption forecasting. J. Volcanol. Geotherm. Res. 261, 144–152 (2013).

    Article  Google Scholar 

  29. 29.

    Auker, M. R., Sparks, R. S. J., Siebert, L., Crosweller, H. S. & Ewert, J. A statistical analysis of the global historical volcanic fatalities record. J. Appl. Volcanol. 2, 2 (2013).

    Article  Google Scholar 

  30. 30.

    Small, C. & Naumann, T. The global distribution of human population and recent volcanism. Glob. Environ. Change Part B Environ. Hazards 3, 93–109 (2001).

    Article  Google Scholar 

  31. 31.

    Chester, D. K., Degg, M., Duncan, A. M. & Guest, J. E. The increasing exposure of cities to the effects of volcanic eruptions: a global survey. Glob. Environ. Change Part B Environ. Hazards 2, 89–103 (2000).

    Article  Google Scholar 

  32. 32.

    Branney, M. J. & Kokelaar, P. Pyroclastic Density Currents and the Sedimentation of Ignimbrites Vol. 27 (Geological Society of London, 2002).

  33. 33.

    Andrews, B. J. & Manga, M. Experimental study of turbulence, sedimentation, and coignimbrite mass partitioning in dilute pyroclastic density currents. J. Volcanol. Geotherm. Res. 225–226, 30–44 (2012). Laboratory experiments of dilute currents illustrate that turbulence plays a fundamental role in the stratification process of PDCs and their buoyancy reversal.

    Article  Google Scholar 

  34. 34.

    Breard, E. et al. Coupling of turbulent and non-turbulent flow regimes within pyroclastic density currents. Nat. Geosci. 9, 767–771 (2016).

    Article  Google Scholar 

  35. 35.

    Dellino, P. et al. Large-scale experiments on the mechanics of pyroclastic flows: design, engineering, and first results. J. Geophys. Res. Solid Earth 112, B04202 (2007).

    Article  Google Scholar 

  36. 36.

    Roche, O. Depositional processes and gas pore pressure in pyroclastic flows: an experimental perspective. Bull. Volcanol. 74, 1807–1820 (2012). Experiments illustrate the role of gas pore pressure in reducing friction and modulating the runout distance of PDCs.

    Article  Google Scholar 

  37. 37.

    Girolami, L., Druitt, T. H., Roche, O. & Khrabrykh, Z. Propagation and hindered settling of laboratory ash flows. J. Geophys. Res. Solid Earth 113, B02202 (2008).

    Article  Google Scholar 

  38. 38.

    Choux, C. M., Druitt, T. H. & Anonymous. Analogue Study of Particle Transport and Sedimentation in Pyroclastic Density Currents (Institut de Physique du Globe de Paris, 2002).

  39. 39.

    Brown, R. J. & Andrews, G. D. M. in The Encyclopedia of Volcanoes 2nd edn (ed. Sigurdsson H.) 631–648 (Academic, 2015).

  40. 40.

    Rowley, P. J., Roche, O., Druitt, T. H. & Cas, R. Experimental study of dense pyroclastic density currents using sustained, gas-fluidized granular flows. Bull. Volcanol. 76, 855 (2014).

    Article  Google Scholar 

  41. 41.

    Girolami, L., Druitt, T. H. & Roche, O. Towards a quantitative understanding of pyroclastic flows: effects of expansion on the dynamics of laboratory fluidized granular flows. J. Volcanol. Geotherm. Res. 296, 31–39 (2015).

    Article  Google Scholar 

  42. 42.

    Freundt, A. Formation of high-grade ignimbrites Part II. A pyroclastic suspension current model with implications also for low-grade ignimbrites. Bull. Volcanol. 60, 545–567 (1999).

    Article  Google Scholar 

  43. 43.

    Doronzo, D. M., de Tullio, M. D., Dellino, P. & Pascazio, G. Numerical simulation of pyroclastic density currents using locally refined Cartesian grids. Comput. Fluids 44, 56–67 (2011).

    Article  Google Scholar 

  44. 44.

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

    Article  Google Scholar 

  45. 45.

    Esposti Ongaro, T., Clarke, A. B., Voight, B., Neri, A. & Widiwijayanti, C. Multiphase flow dynamics of pyroclastic density currents during the May 18, 1980 lateral blast of Mount St. Helens. J. Geophys. Res. Solid Earth 117, B06208 (2012). Three-dimensional, multiphase flow numerical models illuminate several aspects of PDC generation and emplacement, and inform interpretation of PDC deposits.

    Article  Google Scholar 

  46. 46.

    Esposti Ongaro, T., Widiwijayanti, C., Clarke, A. B., Voight, B. & Neri, A. Multiphase-flow numerical modeling of the 18 May 1980 lateral blast at Mount St. Helens, USA. Geology 39, 535–538 (2011).

    Article  Google Scholar 

  47. 47.

    Fisher, R. V. Transport and deposition of a pyroclastic surge across an area of high relief; the 18 May 1980 eruption of Mount St. Helens, Washington. Geol. Soc. Am. Bull. 102, 1038–1054 (1990).

    Article  Google Scholar 

  48. 48.

    Brand, B. D. et al. A combined field and numerical approach to understanding dilute pyroclastic density current dynamics and hazard potential: Auckland Volcanic Field, New Zealand. J. Volcanol. Geotherm. Res. 276, 215–232 (2014).

    Article  Google Scholar 

  49. 49.

    Scott, W. E. et al. in Fire and Mud: Eruptions and Lahars of Mount Pinatubo, Philippines (eds Newhall, C. G. & Punongbayan, R. S.) 545–570 (Univ. Washington Press, 1996).

  50. 50.

    Calder, E. S. et al. Mobility of pyroclastic flows and surges at the Soufriere Hills Volcano, Montserrat. Geophys. Res. Lett. 26, 537–540 (1999).

    Article  Google Scholar 

  51. 51.

    Druitt, T. H. et al. Small-volume, highly mobile pyroclastic flows formed by rapid sedimentation from pyroclastic surges at Soufriere Hills Volcano, Montserrat; an important volcanic hazard. Geol. Soc. Lond. Mem. 21, 263–279 (2002).

    Article  Google Scholar 

  52. 52.

    Loughlin, S. C. et al. Pyroclastic flows and surges generated by the 25 June 1997 dome collapse, Soufriere Hills Volcano, Montserrat. Geol. Soc. Lond. Mem. 21, 191–209 (2002).

    Article  Google Scholar 

  53. 53.

    Lube, G., Cronin, S. J., Thouret, J.-C. & Surono Kinematic characteristics of pyroclastic density currents at Merapi and controls on their avulsion from natural and engineered channels. Geol. Soc. Am. Bull. 123, 1127–1140 (2011).

    Article  Google Scholar 

  54. 54.

    Trolese, M. et al. Very rapid cooling of the energetic pyroclastic density currents associated with the 5 November 2010 Merapi eruption (Indonesia). J. Volcanol. Geotherm. Res. 358, 1–12 (2018).

    Article  Google Scholar 

  55. 55.

    Dufek, J., Esposti Ongaro, T. & Roche, O. in The Encyclopedia of Volcanoes 2nd edn (ed. Sigurdsson H.) 617–629 (Academic, 2015).

  56. 56.

    Breard, E. C. P. & Lube, G. Inside pyroclastic density currents – uncovering the enigmatic flow structure and transport behaviour in large-scale experiments. Earth Planet. Sci. Lett. 458, 22–36 (2017). Large-scale experiments are the only way to reproduce stratified PDCs displaying both concentrated and turbulent behaviour, and to observe the dynamic interaction and continuous transformation between the transport and depositional systems.

    Article  Google Scholar 

  57. 57.

    Andrews, B. J. & Manga, M. Effects of topography on pyroclastic density current runout and formation of coignimbrites. Geology 39, 1099–1102 (2011).

    Article  Google Scholar 

  58. 58.

    Scharff, L., Hort, M. & Varley, N. R. First in-situ observation of a moving natural pyroclastic density current using Doppler radar. Sci. Rep. 9, 7386 (2019).

    Article  Google Scholar 

  59. 59.

    Ripepe, M., De Angelis, S., Lacanna, G. & Voight, B. Observation of infrasonic and gravity waves at Soufrière Hills Volcano, Montserrat. Geophys. Res. Lett. 37, L00E14 (2010).

    Google Scholar 

  60. 60.

    Capra, L. et al. The anatomy of a pyroclastic density current: the 10 July 2015 event at Volcán de Colima (Mexico). Bull. Volcanol. 80, 34 (2018).

    Article  Google Scholar 

  61. 61.

    Ogburn, S. E. FlowDat: Mass Flow Database. Vhub https://vhub.org/resources/2076 (2013).

  62. 62.

    Ogburn, S. E., Loughlin, S. C. & Calder, E. S. DomeHaz: dome-forming eruptions database v2.4. Vhub https://vhub.org/groups/domedatabase (2012).

  63. 63.

    Harnett, C. E. et al. Presentation and analysis of a worldwide database for lava dome collapse events: the Global Archive of Dome Instabilities (GLADIS). Bull. Volcanol. 81, 16 (2019).

    Article  Google Scholar 

  64. 64.

    Ogburn, S. E. & Calder, E. S. The relative effectiveness of empirical and physical models for simulating the dense undercurrent of pyroclastic flows under different emplacement conditions. Front. Earth Sci. 5, 83 (2017).

    Article  Google Scholar 

  65. 65.

    Macorps, E. et al. Stratigraphy, sedimentology and inferred flow dynamics from the July 2015 block-and-ash flow deposits at Volcán de Colima, Mexico. J. Volcanol. Geotherm. Res. 349, 99–116 (2018).

    Article  Google Scholar 

  66. 66.

    Breard, E. C. P., Lube, G., Cronin, S. J. & Valentine, G. A. Transport and deposition processes of the hydrothermal blast of the 6 August 2012 Te Maari eruption, Mt. Tongariro. Bull. Volcanol. 77, 100 (2015).

    Article  Google Scholar 

  67. 67.

    Efford, J. T. et al. Vegetation dieback as a proxy for temperature within a wet pyroclastic density current: a novel experiment and observations from the 6th of August 2012 Tongariro eruption. J. Volcanol. Geotherm. Res. 286, 367–372 (2014).

    Article  Google Scholar 

  68. 68.

    Pensa, A., Capra, L. & Giordano, G. Ash clouds temperature estimation. Implication on dilute and concentrated PDCs coupling and topography confinement. Sci. Rep. 9, 5657 (2019).

    Article  Google Scholar 

  69. 69.

    Wibowo, H. E., Purnama Edra, A., Harijoko, A. & Anggara, F. Emplacement temperature of the overbank and dilute-detached pyroclastic density currents of Merapi 5 November 2010 events using reflectance analysis of associated charcoal. J. Appl. Geol. 3, 41–51 (2018).

    Article  Google Scholar 

  70. 70.

    Maeno, F. et al. Reconstruction of a phreatic eruption on 27 September 2014 at Ontake volcano, central Japan, based on proximal pyroclastic density current and fallout deposits. Earth Planets Space 68, 82 (2016).

    Article  Google Scholar 

  71. 71.

    Fisher, R. V. Models of pyroclastic surges and pyroclastic flows. J. Volcanol. Geotherm. Res. 6, 305–318 (1979).

    Article  Google Scholar 

  72. 72.

    Fisher, R. V. & Schmincke, H.-U. Pyroclastic Rocks (Springer, 1984).

  73. 73.

    Sparks, R. S. J. & Walker, G. P. L. The ground surge deposit: a third type of pyroclastic rock. Nature 241, 62–64 (1973).

    Article  Google Scholar 

  74. 74.

    Wohletz, K. H. in From Magma to Tephra (eds Freundt, A. & Rosi, M.) 247–312 (Elsevier, 1998).

  75. 75.

    Douillet, G. A. et al. Dune bedforms produced by dilute pyroclastic density currents from the August 2006 eruption of Tungurahua volcano, Ecuador. Bull. Volcanol. 75, 1–20 (2013).

    Google Scholar 

  76. 76.

    Douillet, G. A. et al. Saltation threshold for pyroclasts at various bedslopes: wind tunnel measurements. J. Volcanol. Geotherm. Res. 278–279, 14–24 (2014).

    Article  Google Scholar 

  77. 77.

    Sulpizio, R., Mele, D., Dellino, P. & La Volpe, L. Deposits and physical properties of pyroclastic density currents during complex Subplinian eruptions: the AD 472 (Pollena) eruption of Somma-Vesuvius, Italy. Sedimentology 54, 607–635 (2007).

    Article  Google Scholar 

  78. 78.

    Brand, B. D. et al. Dynamics of pyroclastic density currents; conditions that promote substrate erosion and self-channelization; mount St Helens, Washington (USA). J. Volcanol. Geotherm. Res. 276, 189–214 (2014).

    Article  Google Scholar 

  79. 79.

    Yamamoto, T., Takarada, S. & Suto, S. Pyroclastic flows from the 1991 eruption of Unzen Volcano, Japan. Bull. Volcanol. 55, 166–175 (1993).

    Article  Google Scholar 

  80. 80.

    Miyabuchi, Y. Deposits associated with the 1990–1995 eruption of Unzen volcano, Japan. J. Volcanol. Geotherm. Res. 89, 139–158 (1999).

    Article  Google Scholar 

  81. 81.

    Wilson, C. J. N. The role of fluidization in the emplacement of pyroclastic flows: an experimental approach. J. Volcanol. Geotherm. Res. 8, 231–249 (1980).

    Article  Google Scholar 

  82. 82.

    Esposti Ongaro, T., Clarke, A. B., Neri, A., Voight, B. & Widiwijayanti, C. Fluid dynamics of the 1997 Boxing Day volcanic blast on Montserrat, West Indies. J. Geophys. Res. Solid Earth 113, B03211 (2008).

    Article  Google Scholar 

  83. 83.

    Lube, G. et al. Flow and deposition of pyroclastic granular flows: a type example from the 1975 Ngauruhoe eruption, New Zealand. J. Volcanol. Geotherm. Res. 161, 165–186 (2007).

    Article  Google Scholar 

  84. 84.

    Sheridan, M. F. Emplacement of pyroclastic flows: a review. Geol. Soc. Am. 180, 125–136 (1979).

    Google Scholar 

  85. 85.

    Valentine, G. A. Stratified flow in pyroclastic surges. Bull. Volcanol. 49, 616–630 (1987).

    Article  Google Scholar 

  86. 86.

    Druitt, T. Emplacement of the 18 May 1980, lateral blast deposit ENE of Mount St. Helens, Washington. Bull. Volcanol. 54, 554–572 (1992).

    Article  Google Scholar 

  87. 87.

    Dellino, P., Mele, D., Sulpizio, R., La Volpe, L. & Braia, G. A method for the calculation of the impact parameters of dilute pyroclastic density currents based on deposit particle characteristics. J. Geophys. Res. Solid Earth 113, B07206 (2008).

    Article  Google Scholar 

  88. 88.

    Dioguardi, F. & Mele, D. PYFLOW_2.0: a computer program for calculating flow properties and impact parameters of past dilute pyroclastic density currents based on field data. Bull. Volcanol. 80, 28 (2018).

    Article  Google Scholar 

  89. 89.

    Mele, D. et al. Hazard of pyroclastic density currents at the Campi Flegrei Caldera (Southern Italy) as deduced from the combined use of facies architecture, physical modeling and statistics of the impact parameters. J. Volcanol. Geotherm. Res. 299, 35–53 (2015).

    Article  Google Scholar 

  90. 90.

    Burgisser, A. Physical volcanology of the 2,050 BP caldera-forming eruption of Okmok volcano, Alaska. Bull. Volcanol. 67, 497–525 (2005).

    Article  Google Scholar 

  91. 91.

    Burgisser, A. & Bergantz, G. W. Reconciling pyroclastic flow and surge: the multiphase physics of pyroclastic density currents. Earth Planet. Sci. Lett. 202, 405–418 (2002). Analysis of gas–particle and particle–particle interactions allows a better classification of PDC dynamics in terms of their scaling properties.

    Article  Google Scholar 

  92. 92.

    Pope, S. B. Turbulent Flows (Cambridge Univ. Press, 2000).

  93. 93.

    Gardner, J. E., Nazworth, C., Helper, M. A. & Andrews, B. J. Inferring the nature of pyroclastic density currents from tree damage: The 18 May 1980 blast surge of Mount St. Helens, USA. Geology 46, 795–798 (2018).

    Article  Google Scholar 

  94. 94.

    Rowley, P. J., Kokelaar, P., Menzies, M. & Waltham, D. Shear-derived mixing in dense granular flows. J. Sediment. Res. 81, 874–884 (2011).

    Article  Google Scholar 

  95. 95.

    Ciamarra, M. P., Coniglio, A. & Nicodemi, M. Shear instabilities in granular mixtures. Phys. Rev. Lett. 94, 188001 (2005).

    Article  Google Scholar 

  96. 96.

    Goldfarb, D. J., Glasser, B. J. & Shinbrot, T. Shear instabilities in granular flows. Nature 415, 302–305 (2002).

    Article  Google Scholar 

  97. 97.

    Pollock, N. M., Brand, B. D., Rowley, P. J., Sarocchi, D. & Sulpizio, R. Inferring pyroclastic density current flow conditions using syn-depositional sedimentary structures. Bull. Volcanol. 81, 46 (2019).

    Article  Google Scholar 

  98. 98.

    Roche, O. et al. Dynamic pore-pressure variations induce substrate erosion by pyroclastic flows. Geology 41, 1107–1110 (2013).

    Article  Google Scholar 

  99. 99.

    Buesch, D. C. Incorporation and redistribution of locally derived lithic fragments within a pyroclastic flow. Geol. Soc. Am. Bull. 104, 1193–1207 (1992).

    Article  Google Scholar 

  100. 100.

    Roche, O., Buesch, D. C. & Valentine, G. A. Slow-moving and far-travelled dense pyroclastic flows during the Peach Spring super-eruption. Nat. Commun. 7, 10890 (2016).

    Article  Google Scholar 

  101. 101.

    Hoblitt, R. P. Observations of the eruptions of July 22 and August 7, 1980, at Mount St. Helens, Washington (US Geological Survey, 1986).

  102. 102.

    Bursik, M. I. & Woods, A. W. The dynamics and thermodynamics of large ash flows. Bull. Volcanol. 58, 175–193 (1996).

    Article  Google Scholar 

  103. 103.

    Pensa, A., Capra, L., Giordano, G. & Corrado, S. Emplacement temperature estimation of the 2015 dome collapse of Volcán de Colima as key proxy for flow dynamics of confined and unconfined pyroclastic density currents. J. Volcanol. Geotherm. Res. 357, 321–338 (2018).

    Article  Google Scholar 

  104. 104.

    Giordano, G. et al. Thermal interactions of the AD79 Vesuvius pyroclastic density currents and their deposits at Villa dei Papiri (Herculaneum archaeological site, Italy). Earth Planet. Sci. Lett. 490, 180–192 (2018).

    Article  Google Scholar 

  105. 105.

    Brown, R. J. & Branney, M. J. Internal flow variations and diachronous sedimentation within extensive, sustained, density-stratified pyroclastic density currents flowing down gentle slopes, as revealed by the internal architectures of ignimbrites on Tenerife. Bull. Volcanol. 75, 727 (2013).

    Article  Google Scholar 

  106. 106.

    Cas, R. A. F. et al. The flow dynamics of an extremely large volume pyroclastic flow, the 2.08-Ma Cerro Galan ignimbrite, NW Argentina, and comparison with other flow types. Bull. Volcanol. 73, 1583–1609 (2011).

    Article  Google Scholar 

  107. 107.

    Silva Parejas, C., Druitt, T. H., Robin, C., Moreno, H. & Naranjo, J. A. The Holocene Pucon eruption of Volcan Villarrica, Chile; deposit architecture and eruption chronology. Bull. Volcanol. 72, 677–692 (2010).

    Article  Google Scholar 

  108. 108.

    Sparks, R. S. J. Grain size variations in ignimbrites and implications for the transport of pyroclastic flows. Sedimentology 23, 147–188 (1976).

    Article  Google Scholar 

  109. 109.

    Breard, E. C. P., Dufek, J. & Lube, G. Enhanced mobility in concentrated pyroclastic density currents: an examination of a self-fluidization mechanism. Geophys. Res. Lett. 45, 654–664 (2017).

    Article  Google Scholar 

  110. 110.

    Lube, G., Breard, E. C. P., Cronin, S. J. & Jones, J. Synthesizing large-scale pyroclastic flows: experimental design, scaling, and first results from PELE. J. Geophys. Res. Solid Earth 120, 1487–1502 (2015).

    Article  Google Scholar 

  111. 111.

    Dufek, J. & Bergantz, G. W. Suspended load and bed-load transport of particle-laden gravity currents: the role of particle–bed interaction. Theor. Comput. Fluid Dyn. 21, 119–145 (2007).

    Article  Google Scholar 

  112. 112.

    Neri, A. et al. 4D simulation of explosive eruption dynamics at Vesuvius. Geophys. Res. Lett. 34, 28597 (2007).

    Article  Google Scholar 

  113. 113.

    Dellino, P. et al. Experimental evidence links volcanic particle characteristics to pyroclastic flow hazard. Earth Planet. Sci. Lett. 295, 314–320 (2010).

    Article  Google Scholar 

  114. 114.

    Andrews, B. J. Dispersal and air entrainment in unconfined dilute pyroclastic density currents. Bull. Volcanol. 76, 852 (2014).

    Article  Google Scholar 

  115. 115.

    Rodriguez-Sedano, L. A. et al. Influence of particle density on flow behavior and deposit architecture of concentrated pyroclastic density currents over a break in slope: Insights from laboratory experiments. J. Volcanol. Geotherm. Res. 328, 178–186 (2016).

    Article  Google Scholar 

  116. 116.

    Douillet, G. A. et al. Pyroclastic dune bedforms: macroscale structures and lateral variations. Examples from the 2006 pyroclastic currents at Tungurahua (Ecuador). Sedimentology 66, 1531–1559 (2019).

    Article  Google Scholar 

  117. 117.

    Elghobashi, S. On predicting particle-laden turbulent flows. Appl. Sci. Res. 52, 309–329 (1994).

    Article  Google Scholar 

  118. 118.

    Carrara, A., Burgisser, A. & Bergantz, G. W. Lubrication effects on magmatic mush dynamics. J. Volcanol. Geotherm. Res. 380, 19–30 (2019).

    Article  Google Scholar 

  119. 119.

    Crowe, C. T., Schwarzkopf, J. D., Sommerfeld, M. & Tsuji, Y. Multiphase Flows with Droplets and Particles (CRC, 2012).

  120. 120.

    Weit, A., Roche, O., Dubois, T. & Manga, M. Maximum solid phase concentration in geophysical turbulent gas-particle flows: insights from laboratory experiments. Geophys. Res. Lett. 46, 6388–6396 (2019).

    Article  Google Scholar 

  121. 121.

    Chen, C. Investigations on Mesoscale Structure in Gas–Solid Fluidization and Heterogeneous Drag Model. Thesis, Tsinghua Univ. (2016).

  122. 122.

    Chen, C., Li, F. & Qi, H. Modeling of the flue gas desulfurization in a CFB riser using the Eulerian approach with heterogeneous drag coefficient. Chem. Eng. Sci. 69, 659–668 (2012).

    Article  Google Scholar 

  123. 123.

    Wang, W. & Chen, Y. in Advances in Chemical Engineering Vol. 47 (eds Marin, G. B. & Li, J.) 193–277 (Academic, 2015).

  124. 124.

    Stix, J. Flow evolution of experimental gravity currents: implications for pyroclastic flows at volcanoes. J. Geol. 109, 381–398 (2001).

    Article  Google Scholar 

  125. 125.

    Mangeney, A. et al. Erosion and mobility in granular collapse over sloping beds. J. Geophys. Res. Earth Surf. 115, F03040 (2010).

    Article  Google Scholar 

  126. 126.

    Pouliquen, O. & Vallance, J. W. Segregation induced instabilities of granular fronts. Chaos 9, 621–630 (1999).

    Article  Google Scholar 

  127. 127.

    Girolami, L., Roche, O., Druitt, T. H. & Corpetti, T. Particle velocity fields and depositional processes in laboratory ash flows, with implications for the sedimentation of dense pyroclastic flows. Bull. Volcanol. 72, 747–759 (2010).

    Article  Google Scholar 

  128. 128.

    Smith, G. M., Williams, R., Rowley, P. J. & Parsons, D. R. Investigation of variable aeration of monodisperse mixtures: implications for pyroclastic density currents. Bull. Volcanol. 80, 67 (2018).

    Article  Google Scholar 

  129. 129.

    Sulpizio, R., Dellino, P., Doronzo, D. M. & Sarocchi, D. Pyroclastic density currents: state of the art and perspectives. J. Volcanol. Geotherm. Res. 283, 36–65 (2014).

    Article  Google Scholar 

  130. 130.

    Cassar, C., Nicolas, M. & Pouliquen, O. Submarine granular flows down inclined planes. Phys. Fluids 17, 103301 (2005).

    Article  Google Scholar 

  131. 131.

    Breard, E. C. P. et al. The permeability of volcanic mixtures—implications for pyroclastic currents. J. Geophys. Res. Solid Earth 124, 1343–1360 (2019).

    Article  Google Scholar 

  132. 132.

    Li, L. & Ma, W. Experimental study on the effective particle diameter of a packed bed with non-spherical particles. Transp. Porous Media 89, 35–48 (2011).

    Article  Google Scholar 

  133. 133.

    Carman, P. C. Fluid flow through granular beds. Chem. Eng. Res. Des. 75, S32–S48 (1997).

    Article  Google Scholar 

  134. 134.

    Lube, G. et al. Generation of air lubrication within pyroclastic density currents. Nat. Geosci. 12, 381–386 (2019).

    Article  Google Scholar 

  135. 135.

    Cole, P. D. et al. Deposits from dome-collapse and fountain-collapse pyroclastic flows at Soufriere Hills Volcano, Montserrat. Geol. Soc. Lond. Mem. 21, 231–262 (2002).

    Article  Google Scholar 

  136. 136.

    Montserrat, S., Tamburrino, A., Roche, O. & Niño, Y. Pore fluid pressure diffusion in defluidizing granular columns. J. Geophys. Res. Earth Surf. 117, F02034 (2012).

    Article  Google Scholar 

  137. 137.

    Druitt, T. H., Bruni, G., Lettieri, P. & Yates, J. G. The fluidization behaviour of ignimbrite at high temperature and with mechanical agitation. Geophys. Res. Lett. 31, L02604 (2004).

    Article  Google Scholar 

  138. 138.

    Gravina, T., Lirer, L., Marzocchella, A., Petrosino, P. & Salatino, P. Fluidization and attrition of pyroclastic granular solids. J. Volcanol. Geotherm. Res. 138, 27–42 (2004).

    Article  Google Scholar 

  139. 139.

    Druitt, T. H., Avard, G., Bruni, G., Lettieri, P. & Maez, F. Gas retention in fine-grained pyroclastic flow materials at high temperatures. Bull. Volcanol. 69, 881–901 (2007).

    Article  Google Scholar 

  140. 140.

    Iverson, R. M. Regulation of landslide motion by dilatancy and pore pressure feedback. J. Geophys. Res. Earth Surf. 110, F02015 (2005).

    Article  Google Scholar 

  141. 141.

    Chédeville, C. & Roche, O. Autofluidization of collapsing bed of fine particles: implications for the emplacement of pyroclastic flows. J. Volcanol. Geotherm. Res. 368, 91–99 (2018).

    Article  Google Scholar 

  142. 142.

    Valentine, G. A. & Sweeney, M. R. Compressible flow phenomena at inception of lateral density currents fed by collapsing gas-particle mixtures. J. Geophys. Res. Solid Earth 123, 1286–1302 (2018).

    Article  Google Scholar 

  143. 143.

    Chedeville, C. & Roche, O. Autofluidization of pyroclastic flows propagating on rough substrates as shown by laboratory experiments. J. Geophys. Res. Solid Earth 119, 1764–1776 (2014).

    Article  Google Scholar 

  144. 144.

    Chédeville, C. & Roche, O. Influence of slope angle on pore pressure generation and kinematics of pyroclastic flows: insights from laboratory experiments. Bull. Volcanol. 77, 96 (2015).

    Article  Google Scholar 

  145. 145.

    Delannay, R., Valance, A., Mangeney, A., Roche, O. & Richard, P. Granular and particle-laden flows: from laboratory experiments to field observations. J. Phys. D Appl. Phys. 50, 053001 (2017).

    Article  Google Scholar 

  146. 146.

    Calder, E. S., Sparks, R. S. J. & Gardeweg, M. C. Erosion, transport and segregation of pumice and lithic clasts in pyroclastic flows inferred from ignimbrite at Lascar Volcano, Chile. J. Volcanol. Geotherm. Res. 104, 201–235 (2000).

    Article  Google Scholar 

  147. 147.

    Rouse, H. Modern conceptions of the mechanics of fluid turbulence. Trans. ASCE 102, 463–505 (1937).

    Google Scholar 

  148. 148.

    Sher, D. & Woods, A. W. Mixing in continuous gravity currents. J. Fluid Mech. 818, R4 (2017).

    Article  Google Scholar 

  149. 149.

    Druitt, T. H. Pyroclastic density currents. Geol. Soc. Lond. Spec. Publ. 145, 145–182 (1998).

    Article  Google Scholar 

  150. 150.

    Fauria, K. E., Manga, M. & Chamberlain, M. Effect of particle entrainment on the runout of pyroclastic density currents. J. Geophys. Res. Solid Earth 121, 6445–6461 (2016).

    Article  Google Scholar 

  151. 151.

    Sher, D. & Woods, A. W. Experiments on mixing in pyroclastic density currents generated from short-lived volcanic explosions. Earth Planet. Sci. Lett. 467, 138–148 (2017).

    Article  Google Scholar 

  152. 152.

    Benage, M. C., Dufek, J. & Mothes, P. A. Quantifying entrainment in pyroclastic density currents from the Tungurahua eruption, Ecuador: integrating field proxies with numerical simulations. Geophys. Res. Lett. 43, 6932–6941 (2016).

    Article  Google Scholar 

  153. 153.

    Dellino, P., Dioguardi, F., Doronzo, D. M. & Mele, D. The entrainment rate of non-Boussinesq hazardous geophysical gas-particle flows: an experimental model with application to pyroclastic density currents. Geophys. Res. Lett. 46, 12851–12861 (2019).

    Article  Google Scholar 

  154. 154.

    Fullmer, W. D. & Hrenya, C. M. The clustering instability in rapid granular and gas-solid flows. Annu. Rev. Fluid Mech. 49, 485–510 (2017).

    Article  Google Scholar 

  155. 155.

    Agrawal, K., Loezos, P. N., Syamlal, M. & Sundaresan, S. The role of meso-scale structures in rapid gas-solid flows. J. Fluid Mech. 445, 151–185 (2001).

    Article  Google Scholar 

  156. 156.

    Goldhirsch, I. & Zanetti, G. Clustering instability in dissipative gases. Phys. Rev. Lett. 70, 1619–1622 (1993).

    Article  Google Scholar 

  157. 157.

    Garzó, V. Instabilities in a free granular fluid described by the Enskog equation. Phys. Rev. E 72, 021106 (2005).

    Article  Google Scholar 

  158. 158.

    Wylie, J. J. & Koch, D. L. Particle clustering due to hydrodynamic interactions. Phys. Fluids 12, 964–970 (2000).

    Article  Google Scholar 

  159. 159.

    Kajishima, T. & Takiguchi, S. Interaction between particle clusters and particle-induced turbulence. Int. J. Heat Fluid Flow 23, 639–646 (2002).

    Article  Google Scholar 

  160. 160.

    Uhlmann, M. & Doychev, T. Sedimentation of a dilute suspension of rigid spheres at intermediate Galileo numbers: the effect of clustering upon the particle motion. J. Fluid Mech. 752, 310–348 (2014).

    Article  Google Scholar 

  161. 161.

    Capecelatro, J., Desjardins, O. & Fox, R. O. Numerical study of collisional particle dynamics in cluster-induced turbulence. J. Fluid Mech. 747, R2 (2014).

    Article  Google Scholar 

  162. 162.

    Moore, J. G. & Rice, C. J. in Explosive Volcanism: Inception, Evolution, and Hazards Ch. 10 133–142 (The National Academies Press, 1984).

  163. 163.

    Yamasato, H. Quantitative analysis of pyroclastic flows using infrasonic and seismic data at Unzen volcano, Japan. J. Phys. Earth 45, 397–416 (1997).

    Article  Google Scholar 

  164. 164.

    Kelfoun, K., Samaniego, P., Palacios, P. & Barba, D. Testing the suitability of frictional behaviour for pyroclastic flow simulation by comparison with a well-constrained eruption at Tungurahua volcano (Ecuador). Bull. Volcanol. 71, 1057–1075 (2009).

    Article  Google Scholar 

  165. 165.

    Uhira, K., Yamasato, H. & Takeo, M. Source mechanism of seismic waves excited by pyroclastic flows observed at Unzen volcano, Japan. J. Geophys. Res. Solid Earth 99, 17757–17773 (1994).

    Article  Google Scholar 

  166. 166.

    Allstadt, K. E. et al. Seismic and acoustic signatures of surficial mass movements at volcanoes. J. Volcanol. Geotherm. Res. 364, 76–106 (2019).

    Article  Google Scholar 

  167. 167.

    Delle Donne, D. et al. in The Eruption of Soufrière Hills Volcano, Montserrat from 2000 to 2010 Vol. 39 (eds Wadge, G., Robertson, R. E. A. & Voight, B.) (Geological Society of London, 2014).

  168. 168.

    Zobin, V. M., Plascencia, I., Reyes, G. & Navarro, C. The characteristics of seismic signals produced by lahars and pyroclastic flows: Volcán de Colima, México. J. Volcanol. Geotherm. Res. 179, 157–167 (2009).

    Article  Google Scholar 

  169. 169.

    Ripepe, M. et al. Tracking pyroclastic flows at Soufrière Hills volcano. Eos Trans. Am. Geophys. Union 90, 229–230 (2009).

    Article  Google Scholar 

  170. 170.

    Rader, E., Geist, D., Geissman, J., Dufek, J. & Harpp, K. Hot clasts and cold blasts: thermal heterogeneity in boiling-over pyroclastic density currents. Geol. Soc. Lond. Spec. Publ. 396, 67–86 (2015).

    Article  Google Scholar 

  171. 171.

    Porreca, M. et al. Paleomagnetic evidence for low-temperature emplacement of the phreatomagmatic Peperino Albano ignimbrite (Colli Albani volcano, Central Italy). Bull. Volcanol. 70, 877–893 (2008).

    Article  Google Scholar 

  172. 172.

    Sawada, Y., Sampei, Y., Hyodo, M., Yagami, T. & Fukue, M. Estimation of emplacement temperatures of pyroclastic flows using H/C ratios of carbonized wood. J. Volcanol. Geotherm. Res. 104, 1–20 (2000).

    Article  Google Scholar 

  173. 173.

    Scott, A. C. & Glasspool, I. J. Charcoal reflectance as a proxy for the emplacement temperature of pyroclastic flow deposits. Geology 33, 589–592 (2005).

    Article  Google Scholar 

  174. 174.

    Benage, M. et al. Tying textures of breadcrust bombs to their transport regime and cooling history. J. Volcanol. Geotherm. Res. 274, 92–107 (2014).

    Article  Google Scholar 

  175. 175.

    Carter, A. J. & Ramsey, M. S. ASTER-and field-based observations at Bezymianny Volcano: focus on the 11 May 2007 pyroclastic flow deposit. Remote Sens. Environ. 113, 2142–2151 (2009).

    Article  Google Scholar 

  176. 176.

    Spampinato, L., Calvari, S., Oppenheimer, C. & Boschi, E. Volcano surveillance using infrared cameras. Earth-Sci. Rev. 106, 63–91 (2011).

    Article  Google Scholar 

  177. 177.

    Voege, M., Hort, M. & Seyfried, R. Monitoring volcano eruptions and lava domes with Doppler radar. Eos Trans. Am. Geophys. Union 86, 537–541 (2005).

    Article  Google Scholar 

  178. 178.

    Donnadieu, F. in Doppler Radar Observations-Weather Radar, Wind Profiler, Ionospheric Radar, and other Advanced Applications (eds Bech, J. & Chau, J. L.) (IntechOpen, 2012).

  179. 179.

    Vriend, N. M. et al. High-resolution radar measurements of snow avalanches. Geophys. Res. Lett. 40, 727–731 (2013).

    Article  Google Scholar 

  180. 180.

    Andrews, B. J. & Gardner, J. E. Turbulent dynamics of the 18 May 1980 Mount St. Helens eruption column. Geology 37, 895–898 (2009).

    Article  Google Scholar 

  181. 181.

    Sovilla, B., Schaer, M., Kern, M. & Bartelt, P. Impact pressures and flow regimes in dense snow avalanches observed at the Vallée de la Sionne test site. J. Geophys. Res. Earth Surf. 113, F01010 (2008).

    Article  Google Scholar 

  182. 182.

    Calder, E., Wagner, K. & Ogburn, S. in Global Volcanic Hazards and Risk (eds Loughlin, S. C., Sparks, S., Brown, S. K., Jenkins, S. F. & Vye-Brown, C.) 335–342 (Cambridge Univ. Press, 2015).

  183. 183.

    Christen, M., Kowalski, J. & Bartelt, P. RAMMS: numerical simulation of dense snow avalanches in three-dimensional terrain. Cold Reg. Sci. Technol. 63, 1–14 (2010).

    Article  Google Scholar 

  184. 184.

    Hungr, O. & McDougall, S. Two numerical models for landslide dynamic analysis. Comput. Geosci. 35, 978–992 (2009).

    Article  Google Scholar 

  185. 185.

    Kokelaar, B. P. Setting, chronology and consequences of the eruption of Soufrière Hills Volcano, Montserrat (1995–1999). Geol. Soc. Lond. Mem. 21, 1–43 (2002).

    Article  Google Scholar 

  186. 186.

    Fisher, R. V. Decoupling of pyroclastic currents; hazards assessments. J. Volcanol. Geotherm. Res. 66, 257–263 (1995). Describes the PDCs at Unzen, in 1991, that unexpectedly transformed from concentrated granular flows into dilute turbulent currents, with devastating consequences.

    Article  Google Scholar 

  187. 187.

    Ogburn, S. E., Calder, E. S., Cole, P. D. & Stinton, A. J. The effect of topography on ash-cloud surge generation and propagation. Geol. Soc. Lond. Mem. 39, 179–194 (2014).

    Article  Google Scholar 

  188. 188.

    Baxter, P. J. et al. Human survival in volcanic eruptions: Thermal injuries in pyroclastic surges, their causes, prognosis and emergency management. Burns 43, 1051–1069 (2017).

    Article  Google Scholar 

  189. 189.

    Wadge, G. & Aspinall, W. P. A review of volcanic hazard and risk-assessment praxis at the Soufrière Hills Volcano, Montserrat from 1997 to 2011. Geol. Soc. Lond. Mem. 39, 439–456 (2014).

    Article  Google Scholar 

  190. 190.

    Doyle, E. E., Hogg, A. J., Mader, H. M. & Sparks, R. S. J. A two-layer model for the evolution and propagation of dense and dilute regions of pyroclastic currents. J. Volcanol. Geotherm. Res. 190, 365–378 (2010).

    Article  Google Scholar 

  191. 191.

    Kelfoun, K. et al. Simulation of block-and-ash flows and ash-cloud surges of the 2010 eruption of Merapi volcano with a two-layer model. J. Geophys. Res. Solid Earth 122, 4277–4292 (2017). Multilayer, depth-averaged models represent a promising computational approach to describe, in a simple way, the inner structure of PDCs, but still require calibration of the interaction between the concentrated and dilute layer.

    Article  Google Scholar 

  192. 192.

    Kelfoun, K. A two-layer depth-averaged model for both the dilute and the concentrated parts of pyroclastic currents. J. Geophys. Res. Solid Earth 122, 4293–4311 (2017).

    Article  Google Scholar 

  193. 193.

    Shimizu, H. A., Koyaguchi, T. & Suzuki, Y. J. The run-out distance of large-scale pyroclastic density currents: a two-layer depth-averaged model. J. Volcanol. Geotherm. Res. 381, 168–184 (2019).

    Article  Google Scholar 

  194. 194.

    Gueugneau, V., Kelfoun, K. & Druitt, T. Investigation of surge-derived pyroclastic flow formation by numerical modelling of the 25 June 1997 dome collapse at Soufrière Hills Volcano, Montserrat. Bull. Volcanol. 81, 25 (2019).

    Article  Google Scholar 

  195. 195.

    Kelfoun, K. Suitability of simple rheological laws for the numerical simulation of dense pyroclastic flows and long-runout volcanic avalanches. J. Geophys. Res. 116, B08209 (2011).

    Google Scholar 

  196. 196.

    Patra, A. K. et al. Parallel adaptive numerical simulation of dry avalanches over natural terrain. J. Volcanol. Geotherm. Res. 139, 1–21 (2005).

    Article  Google Scholar 

  197. 197.

    Charbonnier, S. J. et al. Evaluation of the impact of the 2010 pyroclastic density currents at Merapi Volcano from high-resolution satellite imagery, field investigations and numerical simulations. J. Volcanol. Geotherm. Res. 261, 295–315 (2013).

    Article  Google Scholar 

  198. 198.

    Esposti Ongaro, T., Orsucci, S. & Cornolti, F. A fast, calibrated model for pyroclastic density currents kinematics and hazard. J. Volcanol. Geotherm. Res. 327, 257–272 (2016).

    Article  Google Scholar 

  199. 199.

    Valentine, G. A. Preface to the topical collection — pyroclastic current models: benchmarking and validation. Bull. Volcanol. 81, 69 (2019).

    Article  Google Scholar 

  200. 200.

    Valentine, G. A., Bonadonna, C., Manzella, I., Clarke, A. & Dellino, P. Large-scale experiments on volcanic processes. Eos Trans. Am. Geophys. Union 92, 89–90 (2011).

    Article  Google Scholar 

  201. 201.

    Pensa, A., Porreca, M., Corrado, S., Giordano, G. & Cas, R. Calibrating the pTRM and charcoal reflectance (Ro%) methods to determine the emplacement temperature of ignimbrites: fogo A sequence, São Miguel, Azores, Portugal, as a case study. Bull. Volcanol. 77, 18 (2015).

    Article  Google Scholar 

Download references

Acknowledgements

This work was supported by the Royal Society of New Zealand Marsden Fund (contract nos. MAU1506 and MAU1902), the National Science Foundation (contract no. EAR 1650382), the New Zealand Ministry of Business, Innovation and Employment’s Endeavour Fund (contract no. RTVU1704) and Resilience to Nature’s Challenges Science Challenge Fund (GNS-RNC047). We thank Michael Manga for the inspiration and help to create the additional figure, and Ermanno Brosch for assisting in the preparation of the figures.

Author information

Affiliations

Authors

Contributions

G.L., E.C.P.B., T.E.-O. and J.D substantially contributed to the discussion of content and wrote and edited the review article. B.B. substantially contributed to the discussion of content and edited the article.

Corresponding author

Correspondence to Gert Lube.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Peer review information

Nature Reviews Earth & Environment thanks S. Ogburn, G. Douillet and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

Publisher’s note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Related links

DomeHaz: https://vhub.org/groups/domedatabase

FlowDat: https://vhub.org/groups/massflowdatabase

GLADIS: http://vhub.org/groups/domecollapse

Supplementary information

Glossary

Gravity currents

When a fluid of one density propagates into a different fluid of contrasting density.

Hazard footprints

The area impacted by one or more hazard(s).

Dynamic pressure

One-half of the product of flow density and the squared flow velocity. A measure of the destructiveness of pyroclastic density currents.

Compressible turbulent flow

Turbulent flow where the density and temperature change with gas pressure.

Pore-pressure-modified granular flow

Granular flow where excess pore pressure is present and can alter the friction force inside the flow.

Dry granular flow

A dense flow of dry granular material whose dynamics are envisaged to be dominated by the stresses associated with particle–particle interactions, rather than hydrodynamic stresses.

Pyroclastic flows

Pyroclastic density currents dominated by concentrated transport.

Pyroclastic surges

Pyroclastic density currents dominated by dilute transport.

Polydispersity

The characteristics of a mixture of particles that contains a range of particle sizes.

Isotropic turbulence

An idealistic state of turbulence, where turbulent fluctuations are assumed to decay statistically uniformly in every direction.

Pore pressure

The pressure of the fluid contained in the interstices of a granular medium.

Subgrid models

The representation of physical processes occurring at scales that are not resolved on a computational mesh.

Monodisperse

A mixture of particles with equivalent size.

Mesoscale particle clusters

Gatherings of particles into coherent band-like structures.

Kolmogorov scale

The length, time and velocity scales in turbulent flows below which the effects of molecular viscosity are non-negligible.

Kelvin–Helmholtz instabilities

A hydrodynamic instability in which immiscible, incompressible and inviscid fluids are in relative and irrotational motion.

Lift-off distances

The distance at which the flow density becomes lower than that of ambient air, resulting in the buoyant rise of part of the pyroclastic density current.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Lube, G., Breard, E.C.P., Esposti-Ongaro, T. et al. Multiphase flow behaviour and hazard prediction of pyroclastic density currents. Nat Rev Earth Environ (2020). https://doi.org/10.1038/s43017-020-0064-8

Download citation