1. Lava Domes
29 March 2019

2. Importance of lava domes
Lava domes really can be considered as “corks” in a champagne bottle…the analogy is a good one
It is RARE to see no explosive activity associated with lava domes
Lava domes are important in terms of TRANSITIONS between effusive and explosive activity

3. STRUCTURE OF THE LECTURE
1. Morphology
Repeating signals and the
effusive-explosive transition
3. Some general laws

4. Growth rates of lava domes

5. Lava dome advection and solidification times
tS = solidification time
tA = advection time
Dimensionless number B :
Fink JH, Griffiths RW (1998) J Geophys Res 103:

6. Lava dome
morphology
Fink JH, Griffiths RW (1998) J Geophys Res 103:

7. Side views of the four analogue domes from the previous page
Fink JH, Griffiths RW (1998) J Geophys Res 103:

8. Lava dome advection and solidification times
tS = solidification time
tA = advection time
Dimensionless number B :
Fink JH, Griffiths RW (1998) J Geophys Res 103:

9. Unzen lava dome, late May 1991

10. Soufrière St. Vincent lava dome, 1979

11. Early Mt. St. Helens lava dome, 1980

12. Venusian “pancake” domes

13. 1. Morphology
2. Repeating signals and the
effusive-explosive transition
3. Some general laws

14. Volcano seismicity (“VT event”)
[or long period earthquake (“lp event”)]
courtesy USGS

15. Mt. St. Helens (USA)

16. 2004-2008 lava dome vent area glacier vent 1980’s lava dome glacier
18 May 1980 collapse amphitheatre
vent area
glacier
vent
Thermal infrared image
1980’s lava dome glacier
Iverson et al. (2006) Nature 444:

17. Lava dome evolution,
(about km3 extruded in ~15 months)
Iverson et al. (2006) Nature 444:

18. Seismogram of the dome, 1 Dec 2005
Iverson et al. (2006) Nature 444:

19. Stick-slip model of dome extrusion
Iverson et al. (2006) Nature 444:

20. Soufrière Hills (Montserrat)

22. Lava dome behaviour, May 1997
Significant lava dome collapses and pyroclastic flows (block and ash flows) associated with these peaks in activity
Voight et al. (1999) Science 283:

23. Block and ash flow deposits (Merapi, Indonesia)
lava dome fragment

24. Lava dome growth,

26. Largest dome collapse at Montserrat: July 2003
collapse peak at 0335 hours local time
Herd et al. (2005) J Volcanol Geotherm Res 148:

27. Vulcanian explosions associated with the dome collapse
Herd et al. (2005) J Volcanol Geotherm Res 148:

28. SO2 gas release (no solid material)
Vulcanian eruptions
SO2 gas release (no solid material)
SPACING
COLUMN HEIGHT

29. Galeras (Colombia)

32. Summer 1992

33. Long period seismic signals associated with
dome destruction and vulcanian eruptions at Galeras (“tornillos”)
These events are a manifestation of pressurization within the shallow plumbing system of the volcano
Narváez M L et al. (1997) J Volcanol Geotherm Res 77:

34. Tornillos with slowly decaying coda
Narváez M L et al. (1997) J Volcanol Geotherm Res 77:

35. Remarkable tornillo signals
Narváez M L et al. (1997) J Volcanol Geotherm Res 77:

36. Key changes before vulcanian eruptions at Galeras
14 January 1993 eruption March 1993 eruption June 1993 eruption
The “h” term in (c ) is a damping coefficient…low values correspond to gradually decaying tornillos, while higher values correspond to a more rapidly decaying tornillo
Gómez M DM, Torres C RA (1997) J Volcanol Geotherm Res 77:

37. 1. Morphology
2. Repeating signals and the effusive-explosive transition
3. Some general laws

38. The fragmentation threshold
Spieler et al. (2004) Earth Planet Sci Lett 226:

39. Viscous behaviour of fluids
Courtesy Wikipedia

40. Shear-thinning behaviour
Lava dome rheology
Shear-thinning behaviour
Note the alignment and breakage of crystals
log  = (8974 / T) – (0.543 log )
= apparent viscosity in Pa s
T = temperature in C
 = strain rate in s-1
Lavallée et al. (2007) Geology 35: