Physical Volcanology

Christoph Breitkreuz,

TU Bergakademie Freiberg

55

Structure:

– Introduction

– Reology and deformation of magma and lava

– Eruption processes and types

– Volcano forms

– Emplacement of lava flows, domes and subvolcanic bodies

– Pyroclastic fragmentation

– Pyroclasts: Types and classification

– Pyroclastic transport und deposition

– Subaquatic and phreatomagmatic processes and resulting textures

– Cooling textures in SiO2-rich (sub-)volcanic bodies

– Volcanic hazards: Assessment and monitoring

exercises: Wednesdays, even weeks, 11.00 – 12.30, CVT

GP Osteifel: 1. – 3.7.2011

Test 18.7.2011

Recommended literature

BRANNEY, M. & KOKELAAR, P. (2002): Pyroclastic density flows and the sedimentation of

ignimbrites.- Geol. Soc. London, Mem., 27, 143 pp.

CAS, R.A.F. & WRIGHT, J.V. (1987): Volcanic successions - Modern and ancient.-

Allen & Unwin, London, 528S.

CHAPIN, C. E. and ELSTON, W. E. (eds.)(1979): Ash-flow tuffs.- Geol. Soc. Amer.

Spec. Pap. 180, 211S.

CHESTER, D.K., DUNCAN, A.M., GUEST, J.E. & KILBURN, C.R.J. (1985): Mount

Etna: Anatomy of a volcano.- Chapman and Hall, London, 404S.

DRUITT, T.H. (1999): Santorini volcano.- Geol. Soc. London, Mem. 19, 165 pp.

DRUITT, T.H. & KOKELAAR, B.P. (eds.)(2002): The eruption of Soufrière Hills

Volcano, Montserrat, from 1995 to 1999.- Geol. Soc. Mem. 21, 645S.

FISHER, R.V. & SCHMINCKE, H.-U. (1984): Pyroclastic rocks.- Springer-Verlag,

Berlin, 472S.

FISHER, R.V. and SMITH, G.A. (eds.)(1991): Sedimentation in volcanic settings.-

Soc. Econ. Paleont. Mineral., Vol. 45.

FRANCIS, P. (1993): Volcanoes - A planetary perspective.- Oxford Univ. Press,

Oxford, 1-443.

FREUNDT, A. & ROSI, M. (Hrsg.)(1998): From magma to tephra – modelling

physical processes of explosive volcanic eruptions.- Developments in Volcanol. 4,

Elsevier, 318S.

GIFKINS, C. , HERRMANN, W. & LARGE, R. (2005): Altered Volcanic Rocks: A

guide to description and interpretation.- Univ. Tasmania, Centre for Ore Deposits

and Exploration Studies, Hobart, 275S.

LATTER, J. (ed.)(1989): Volcanic hazards.- Springer, 625S.

LIPMAN, P.W. & MULLINEAUX, D.R. (eds.)(1981): The 1980 eruptions of Mount St.

Helens, Wash., USA.- U.S. Geol. Surv. Prof. Pap., 1250, ca. 850S.

MARTÍ, J. & ERNST, G.G. (eds.)(2005): Volcanoes and the environment.- Cambridge

University Press, 471 pp.

McCLELLAND, L. et al. (eds.)(1989): Global volcanism, 1975-1985.- Amer. Geophys.

Union, Wash. D.C., 655S.

McPHIE, J.M., DOYLE, M. & ALLEN, R. (1993): Volcanic textures - A guide to the

interpretation of textures in volcanic rocks.- Univ. Tasmania, Centre for Ore

Deposits and Exploration Studies, 1-196, Hobart.

ORTON, G.J. (1996): Volcanic environment. - in: READING, H.G. (Hrsg.):

Sedimentary Environments: Processes, facies and stratigraphy. - Blackwell

Science, Oxford, 3. Aufl., 485-567.

SCHMINCKE, H.-U. (2004): Volcanism.- Springer, Heidelberg, 324 pp.

SIGURDSON, H. et al. (eds.)(1999): Encyclopedia of volcanoes.- Academic Press.

SIMKIN, T. and FISKE, R.S. (1983): Krakatau 1883 - The eruption and its effects.-

Smithsonian Inst. Press. 464S.

THOMPSON, D. (2000): The volcano cowboys - The rocky evolution of a dangerous science.-

St. Martin‘s Press, New York, 326 pp.

WHITE, J.D.L., SMELLIE, J.L. & CLAGUE, D.A. (eds.)(2003): Explosive Subaqueous

volcanism.- Geophys. Monogr., 140, 1-379.

Journal of Volcanology and Geothermal Research (Elsevier)

Bulletin of Volcanology (International Association of Volcanology and Chemistry of

the Earths Interior, IAVCEI), www.iavcei.org

http://vulcan.wr.usgs.gov/home.html

www.geo.tu-freiberg.de/dynamo/Abbildungen_Lehre.htm

Physical volcanology Petrology Sedimentology

Natural Hazards

Mineral deposits

e.g. VHMS Raw material

Agriculture

Engineering

Geology

Hydrology

Health

Fields of work and position within Geosciences

History of

volcanology –

Historic eruptions

Encyclopedia of Volcanoes 1999

Aristotheles

Plato

A.G. Werner

J. Hutton

Santorini, Ägäis

Forque 1879

Dietrich, ETH Zürich

1650 B.C...

Encyclopedia of Volcanoes 1999

History of

volcanology –

Historic eruptions

Vesuv 79 A.D.

Pompei

Encyclopedia of Volcanoes 1999

History of

volcanology –

Historic eruptions

Krakatau 1883 in Indonesia:

Tsunami caused by a shallow marine caldera eruption:

36 000 fatalities

Encyclopedia of Volcanoes 1999

History of

volcanology –

Historic eruptions

Lacroix 1904

Mt. Pelee, Martinique: 1902-3

St. Pierre

Lassen Peak, 1915,

California

Encyclopedia of Volcanoes 1999

History of

volcanology –

Historic eruptions

Mt. St. Helens, Washington

June 1980

Pinatubo 1991

Smithsonian Institute

Schmincke 1986

Bahlburg & Breitkreuz 2004

Plate tectonics and

magma generation

Irvine & Baragar 1971

Geochemical

classification

older classifications

Required: Norm

calculation

(e.g. CIPW)

Al2O3 content

Reology and

Deformation of Magma

and Lava

Christoph Breitkreuz,

TU Bergakademie Freiberg

Sill, Estratos El Bordo, Chile

Mt. St. Helens

Glass Mtns, California

welded ignimbrite,

St. Francis Mtns, Missouri,

Proterozoic

Reology, deformation and fragmentation are controlled by

many parameters. The following are important:

- Ambient pressure (in the magmatic conduit

system, in subaquatic environment)

- Viscosity of Magma/Lava

- Density of Magma/Lava

- Temperature

- Deformation rate

- Magma ascent rate

Just to remember…

Types of fluids: Newtonian Fluid: water,

certain pyroclastic flows

Bingham Fluid:

(with yield strength)

Debris flows, lava / magma

certain pyroclastic flows

Fig. 1.1 Relationship between viscosity

and temperature for some magmas. The

rhyolite was glassy or liquid through the

entire temperature range (From Cas &

Wright 1987, after Murase & McBirney

1973).

VISCOSITY depends on:

- composition

(SiO2 , Al2O3 )

(H2O, other volatiles, Na, K etc. )

- temperature

- phenocryst content

- microlith content,

- vesicle content

Table 1.1 Estimates of eruption temperatures for some common magmas (After Cas & Wright 1987).

Fig. 1.2 The effect of H2O on the viscosity

of (a) granitic and (b) basaltic melts at

varying temperatures (From Cas & Wright

1987, after Murase 1962).

H2O content and Viscosity:

e.g. foaming up of magma during ascent

(first boiling)

Basalt

Rhyolite

Fig. 1.3 Densities of some molten volcanic

rocks with varying temperature at atmospheric

pressure (From Cas & Wright 1987, after

Murase & McBirney 1973).

Density depends on:

composition

temperature

pressure

content of phenocrysts

and vesicles

Fig. 1.5 Relation between super cooling (T) and

crystal nucleation and growth rate in a granitic melt

(Swanson et al. 1989)

T = supercooling

(below liquidus)

Formation of crystals and vesicles depends on:

- temperature

- presuure

- time (Nucleation and diffusion!)

Fig. 1.6 Bubble growth and water oversaturation in an ascending rhyolitic magma. The curves

define oversaturation in % as a function of the depth in the system during magma ascent. The

labels on the curves refer to the ascent or rise rates. The initial conditions are 4 km (a) and 1 km

(b), which correspond to initial water concentrations dissolved in the magma of 3.72 and 1.86

wt.%, respectively. Reproduced from Proussevitch and Sahagian (1996) (From Dingwell 1998).

FIRST BOILING:

- ascent rate

- supersaturation (e.g., with respect to H2O)

(m

)

Embayments in quartz phenocrysts

Embayments form by:

- growth impediment

- skeletal growth

(quenching)

Growth zonation

Cathodoluminescence

image of a quartz

phenocryst

Quartz broken during first boiling

Ignimbrite with crystal fragments

Fig. 1.4 Relation between deformation rate and

deformation style of magma or lava depending

on temperature; Tg = glass transition temperature

Fig. 1.7 Temperature profiles of the Ben Lomond

flow at different time steps as derived by numerical

modelling with the emplacement temperature of

850°C; Tg = glass transition temperature, FVP =

finely vesicular pumice, U.OBS = upper obsidian,

TZ = transition zone, RHY = stony rhyolite, L.OBS

= lower obsidian, BRX = breccia (from Stevenson et

al. 2001)

Land surface

Tg = glass transition temperature

c. 2/3 of the liquidus temperature

Glass (above Tg) oozes out of a fracture plain

Panum Crater, Mono Lake, California