Bulletin of Volcanology

, 77:96 | Cite as

Influence of slope angle on pore pressure generation and kinematics of pyroclastic flows: insights from laboratory experiments

  • Corentin ChédevilleEmail author
  • Olivier Roche
Research Article


The influence of slope angle on pore pressure generation and kinematics of fines-rich pyroclastic flows was investigated through laboratory experiments. Granular flows were generated by the release of a column of fine glass beads (d = 0.08 mm) in an inclined channel (0–30°). The granular column could be fluidized while the channel base was either smooth or made rough by glued beads of 3 mm diameter. Pore pressure measurements reveal that the degree of autofluidization, caused by air escaping from the substrate interstices into which flow particles settled, was high at all slope angles. Flow runout increase due to autofluidization, however, was reduced at slope angle higher than ∼12° because of the occurrence of a strong deceleration phase that limited the flow duration. This is probably caused by the combination of flow head thinning at increased slope angle and settling of particles into the substrate interstices until the flow ran out of mass. Analysis of high-speed videos suggests that ingestion of ambient air at the flow front did not occur, even on steep slopes of 30°. Experiments at inclinations close to (25°) or slightly higher (30°) than the repose angle of the granular material (28.5°) revealed the formation of a thin basal deposit that was then eroded as the flow thickness and velocity gradually decreased. Our study suggests that air escape from substrate interstices in nature can be a significant external cause of pore pressure generation that favors low energy dissipation and long runout distances of pyroclastic flows on moderate topographies.


Pyroclastic flows Fluidization Pore pressure Analog modelling Inclined substrate Substrate roughness 



We are grateful to Greg Valentine and David Jessop for the interesting discussions and comments that helped to improve the manuscript. We thank the associate editor Gert Lube, Ben Andrews, and Eric Bréard for the careful and constructive reviews. This work was financed by the Laboratoire Mixte International SVAN of Institut de Recherche pour le Développement (IRD, France) and by the French Government Laboratory of Excellence initiative n°ANR-10-LABX-0006, the Région Auvergne and the European Regional Development Fund. This is Laboratory of Excellence ClerVolc contribution number 169.


  1. Allen JRL (1971) Mixing at turbidity current heads, and its geological implications. J Sediment Petrol 41:97–113CrossRefGoogle Scholar
  2. Andrews BJ (2014) Dispersal and air entrainment in unconfined dilute pyroclastic density currents. Bull Volcanol 76:852, doi: 8 10.1007/s00445-00014-00852-00444Google Scholar
  3. Andrews BJ, Manga M (2012) Experimental study of turbulence, sedimentation, and coignimbrite mass partitioning in dilute pyroclastic density currents. J Volcanol Geotherm Res 225–226:30–44. doi: 10.1016/j.jvolgeores.2012.1002.1011 CrossRefGoogle Scholar
  4. Artoni R, Santomaso AC, Canu P (2009) Effective boundary conditions for dense granular flows. Phys Rev E 79:031304. doi: 10.1103/PhysRevE.79.031304 CrossRefGoogle Scholar
  5. Bareschino P, Lirer L, Marzocchella A, Petrosino P, Salatino P (2008) Self-fluidization of subaerial rapid granular flows. Powder Technol 182:323–333. doi: 10.1016/j.powtec.2007.12.010 CrossRefGoogle Scholar
  6. Bernard J, Kelfoun K, Le Pennec J-L, Vallejo Vargas S (2014) Pyroclastic flow erosion and bulking processes: comparing field-based vs. modeling results at Tungurahua volcano, Ecuador. Bull Volcanol 76:858. doi: 10.1007/s00445-014-0858-y CrossRefGoogle Scholar
  7. Brand BD, Mackaman-Lofland C, Pollock NM, Bendaña S, Dawson B, Wichgers P (2014) 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. doi: 10.1016/j.jvolgeores.2014.01.007 CrossRefGoogle Scholar
  8. Branney MJ, Kokelaar BP (2002) Pyroclastic density currents and the sedimentation of ignimbrites. Geol Soc Lond Mem 27Google Scholar
  9. Brown RJ, Branney MJ (2004) Bypassing and diachronous deposition from density currents: evidence from a giant regressive bed form in the Poris ignimbrite, Tenerife, Canary Islands. Geology 32:445–448. doi: 10.1130/G20188.1 CrossRefGoogle Scholar
  10. Brown RJ, Branney MJ (2013) 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. doi: 10.1007/s00445-013-0727-0 CrossRefGoogle Scholar
  11. Calder ES, Sparks RSJ, Gardeweg MC (2000) Erosion, transport and segregation of pumice and lithic clasts in pyroclastic flows inferred from ignimbrite at Lascar Volcano, Chile. J Volcanol Geotherm Res 104:201–235CrossRefGoogle Scholar
  12. Chédeville C, Roche O (2014) Autofluidization of pyroclastic flows propagating on rough substrates as shown by laboratory experiments. J Geophys Res 119:1764–1776. doi: 10.1002/2013JB010554 CrossRefGoogle Scholar
  13. Druitt TH (1998) Pyroclastic density currents. Geol Soc Lond Spec Publ 145–182Google Scholar
  14. Druitt TH, Avard G, Bruni G, Lettieri P, Maez F (2007) Gas retention in fine-grained pyroclastic flow materials at high temperatures. Bull Volcanol 69:881–901. doi: 10.1007/s00445-007-0116-7 CrossRefGoogle Scholar
  15. Farin M, Mangeney A, Roche O (2014) Fundamental changes of granular flow dynamics, deposition, and erosion processes at high slope angles: insights from laboratory experiments. J Geophys Res 119:504–532. doi: 10.1002/2013JF002750 CrossRefGoogle Scholar
  16. Fisher R, Orsi G, Ort M, Heiken G (1993) Mobility of a large-volume pyroclastic flow—emplacement of the Campanian ignimbrite, Italy. J Volcanol Geotherm Res 56:205–220CrossRefGoogle Scholar
  17. GDR MiDi (2004) On dense granular flows. Eur Phys J E 14:341–365. doi: 10.1140/epje/i2003-10153-0
  18. Giordano G (1998) The effect of paleotopography on lithic distribution and facies associations of small volume ignimbrites: the WTT Cupa (Roccamonfina volcano, Italy). J Volcanol Geotherm Res 87:255–273CrossRefGoogle Scholar
  19. Girolami L, Druitt TH, Roche O, Khrabrykh Z (2008) Propagation and hindered settling of laboratory ash flows. J Geophys Res 113:B02202. doi: 10.1029/2007JB005074 Google Scholar
  20. Iverson RM (1997) The physics of debris flows. Rev Geophys 35:245–296CrossRefGoogle Scholar
  21. Lube G, Cronin SJ, Platz T, Freundt A, Procter JN, Henderson C, Sheridan MF (2007) Flow and deposition of pyroclastic granular flows: a type example from the 1975 Ngauruhoe eruption, New Zealand. J Volcanol Geotherm Res 161:165–186. doi: 10.1016/j.jvolgeores.2006.12.003 CrossRefGoogle Scholar
  22. Lube G, Huppert HE, Sparks RSJ, Freundt A (2011) Granular column collapses down rough, inclined channels. J Fluid Mech 675:347–368. doi: 10.1017/jfm.2011.21 CrossRefGoogle Scholar
  23. Lucas A, Mangeney A (2007) Mobility and topographic effects for large Valles Marineris landslides on Mars. Geophys Res Lett 34:L10201. doi: 10.1029/2007GL029835 CrossRefGoogle Scholar
  24. Lucas A, Mangeney A, Ampuero JP (2014) Frictional velocity-weakening in landslides on Earth and on other planetary bodies. Nat Commun 5:3417. doi: 10.1038/ncomms4417 Google Scholar
  25. Mangeney A, Bouchut F, Thomas N, Vilotte JP, Bristeau MO (2007) Numerical modeling of self-channeling granular flows and of their levee-channel deposit. J Geophys Res 112:F02017. doi: 02010.01029/02006JF000469Google Scholar
  26. Mangeney A, Roche O, Hungr O, Mangold N, Faccanoni G, Lucas A (2010) Erosion and mobility in granular collapse over sloping beds. J Geophys Res 115:1–21. doi: 10.1029/2009JF001462 Google Scholar
  27. McTaggart K (1960) The mobility of nuées ardentes. Am J Sci 258:369–382CrossRefGoogle Scholar
  28. Montserrat S, Tamburrino A, Roche O, Niño Y (2012) Pore fluid pressure diffusion in defluidizing granular columns. J Geophys Res 117:F02034. doi: 10.1029/2011JF002164 Google Scholar
  29. Rhodes MJ (1998) Introduction to particle technology. John Wiley, ChichesterGoogle Scholar
  30. Roche O (2012) Depositional processes and gas pore pressure in pyroclastic flows: an experimental perspective. Bull Volcanol 74:1807–1820. doi: 10.1007/s00445-012-0639-4 CrossRefGoogle Scholar
  31. Roche O, Gilbertson MA, Phillips JC, Sparks RSJ (2006) The influence of particle size on the flow of initially fluidized powders. Powder Technol 166:167–174. doi: 10.1016/j.powtec.2006.05.010 CrossRefGoogle Scholar
  32. Roche O, Montserrat S, Niño Y, Tamburrino A (2010) Pore fluid pressure and internal kinematics of gravitational laboratory air-particle flows: insights into the emplacement dynamics of pyroclastic flows. J Geophys Res 115:B09206. doi: 10.1029/2009JB007133 Google Scholar
  33. Roche O, Attali M, Mangeney A, Lucas A (2011) On the run-out distance of geophysical gravitational flows: insight from fluidized granular collapse experiments. Earth Planet Sci Lett 311:375–385. doi: 10.1016/j.epsl.2011.09.023 CrossRefGoogle Scholar
  34. Roche O, Niño Y, Mangeney A, Brand B, Pollock N, Valentine G (2013) Dynamic pore pressure variations induce substrate erosion by pyroclastic flows. Geology 41:1107–1110. doi: 10.1130/G34668.1 CrossRefGoogle Scholar
  35. Rowley PJ, Roche O, Druitt TH, Cas R (2014) Experimental study of dense pyroclastic density currents using sustained, gas-fluidized granular flows. Bull Volcanol 76:855. doi: 10.1007/s00445-014-0855-1 CrossRefGoogle Scholar
  36. Simpson JE (1972) Effects of the lower boundary on the head of a gravity current. J Fluid Mech 53:759. doi: 10.1017/S0022112072000461 CrossRefGoogle Scholar
  37. Simpson JE (1986) Mixing at the front of a gravity current. Acta Mech 63:245–253. doi: 10.1007/BF01182551 CrossRefGoogle Scholar
  38. Simpson JE (1997) Gravity currents in the environment and the laboratory. Cambridge University Press, CambridgeGoogle Scholar
  39. Sparks RSJ (1976) Grain size variations in ignimbrites and implications for the transport of pyroclastic flows. Sedimentology 23:147–188CrossRefGoogle Scholar
  40. Sparks RSJ, Gardeweg M, Calder E, Matthews SJ (1997) Erosion by pyroclastic flows on Lascar Volcano. Chile. Bull Volcanol 58:557–565CrossRefGoogle Scholar
  41. Valentine G, Buesch D, Fisher R (1989) Basal layered deposits of the peach springs tuff, northwestern Arizona, USA. Bull Volcanol 51:395–414CrossRefGoogle Scholar
  42. Williams R, Branney MJ, Barry TL (2013) Temporal and spatial evolution of a waxing then waning catastrophic density current revealed by chemical mapping. Geology 42:107–110. doi: 10.1130/G34830.1 CrossRefGoogle Scholar
  43. Wilson C (1980) The role of fluidization in the emplacement of pyroclastic flows: an experimental approach. J Volcanol Geotherm Res 8:231–249CrossRefGoogle Scholar
  44. Wilson C, Houghton B, Kamp PJJ, McWilliams MO (1995) An exceptionally widespread ignimbrite with implications for pyroclastic flow emplacement. Nature 378:605–607CrossRefGoogle Scholar
  45. Woods AW, Bursik M, Kurbatov A (1998) The interaction of ash flows with ridges. Bull Volcanol 60:38–51CrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2015

Authors and Affiliations

  1. 1.Laboratoire Magmas et VolcansUniversité Blaise Pascal, CNRS, IRD, OPGCClermont-FerrandFrance

Personalised recommendations