Lava Domes 29 March 2019 Importance of lava

Lava Domes 29 March 2019 Importance of lava

Lava Domes 29 March 2019 Importance of lava domes Lava domes really can be considered as corks in a champagne bottlethe 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 STRUCTURE OF THE

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

Growth rates of lava domes Lava dome advection and solidification times tS = solidification time tA = advection time

Dimensionless number B : Fink JH, Griffiths RW (1998) J Geophys Res 103:527-545 Lava dome morphology

Fink JH, Griffiths RW (1998) J Geophys Res 103:527-54 ide views of the four analogue omes from the previous page Fink JH, Griffiths RW (1998) J Geophys Res 103:527-54

Lava dome advection and solidification times tS = solidification time tA = advection time Dimensionless number B : Fink JH, Griffiths RW (1998) J Geophys Res 103:527-545

Unzen lava dome, late May 1991 Soufrire St. Vincent lava dome, 1979

Early Mt. St. Helens lava dome, 1980 Venusian pancake domes 1. Morphology 2. Repeating signals and the

effusive-explosive transition 3. Some general laws Volcano seismicity (VT event)

[or long period earthquake (lp event)] courtesy USGS Mt. St. Helens (USA) 2004-2008 lava dome

18 May 1980 collapse amphitheatre vent area glacier vent

Thermal infrared image 1980s lava dome glacier Iverson et al. (2006) Nature 444:439-443

Lava dome evolution, 2004-2005 verson et al. (2006) Nature 444:439-443 (about 0.072 km3 extruded in ~15 months)

Seismogram of the dome, 1 Dec 2005 Iverson et al. (2006) Nature 444:439-44 Stick-slip model of dome

extrusion Iverson et al. (2006) Nature 444:439-44 Soufrire Hills (Montserrat) 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 283:1138-11

Block and ash flow deposits (Merapi, Indonesia) lava dome fragment ava dome growth,

2002-2003 Largest dome collapse at Montserrat: July 2003 collapse peak at 0335 hours local time

Herd et al. (2005) J Volcanol Geotherm Res 148:234-25 Vulcanian explosions associated with the dome collapse Herd et al. (2005) J Volcanol Geotherm Res 148:234-25

Vulcanian eruptions Vulcanian eruptions at SHV, July 2003 6 Event number

5 SO2 gas release (no solid material) 4

3 SPACING 2 1 0 0

1000 2000 3000

4000 5000 6000 Vulcanian eruptions at SHV, July 2003

Elapsed time since collapse maximum (min) Column height (km) 20

15 10 COLUMN HEIGHT 5

0 0 1000 2000

3000 4000 Elapsed time since collapse maximum (min) 5000

6000 Galeras (Colombia) Summer 1992

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

Narvez M L et al. (1997) J Volcanol Geotherm Res 77:159-1 Tornillos with slowly decaying coda

arvez M L et al. (1997) J Volcanol Geotherm Res 77:159-171 Remarkable tornillo signals Narvez M L et al. (1997) J Volcanol Geotherm Res 77:159-1 Key changes before vulcanian eruptions at

Galeras 14 January 1993 eruption 23 March 1993 eruption 7 June 1993 eruption

The h term in (c ) is a damping coefficientlow values correspond to gradually decaying tornillos, while higher values correspond to a more rapidly decaying tornillo Gmez M DM, Torres C RA (1997) J Volcanol Geotherm Res 77:173- 1. Morphology 2. Repeating signals and

the effusive-explosive transition 3. Some general laws The fragmentation threshold Spieler et al. (2004) Earth Planet Sci Lett 226:139-148

Viscous behaviour of fluids Courtesy Wikipedia Lava dome rheology

Note the alignment and breakage of crystals log = -0.993 + (8974 / T) (0.543 log ) = apparent viscosity in Pa s T = temperature in C = strain rate in s-1

avalle et al. (2007) Geology 35:843-846 Shear-thinning behaviour

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