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Nature and efficiency of pyroclast generation from porous magma: Insights from field investigations and laboratory experiments
Author(s)
Institution
Earth & Environmental Sciences, University of Munich (LMU)
Language
English
Status
Published
Refereed
Yes
Issued date
December 4, 2005
Alternative Location
Theses type
PhD dissertation
Abstract
Enhanced knowledge of pre- and syn-eruptive processes is vital to deal with the increasing threat imposed to population and infrastructure by volcanoes that have been active historically and may potentially erupt in future. For many years, most of this knowledge was received from experiments on analogue materials and/or numerical models. In order to increase their significance and applicability for the “real” case, the natural complexity may not be oversimplified and the input parameters must be reliable and realistic. In the light of this, a close connection of field and laboratory work is essential. Volcanic eruptions may be phreatic, phreatomagmatic or magmatic, the latter scenario of which was addressed in this study. Rising magma is subject to decreasing lithostatic pressure. As a direct consequence, volatiles become increasingly oversaturated and bubbles will nucleate and grow depending on initial volatile content and melt viscosity. Both factors directly influence the diffusivity that limits the rate of bubble growth. Increasing amounts of bubbles increase the buoyancy difference to the surrounding rocks and lead to an acceleration of the rising melt-bubble mixture. Beside these limiting factors, the overpressure in the gas bubbles greatly depends on the magma’s ascent speed as it controls the residence time to conditions favourable to degassing (a combination of lithostatic pressure and magma temperature) and the time of overpressure reduction due to degassing. Volcanic eruptions occur when the bubbly melt can no longer withstand the exerted stress that derives from the overlying weight (lithostatic pressure), the expanding gas bubbles (internal gas overpressure) and different ascent velocities in the conduit (velocity profile). The melt will be fragmented and the gas-pyroclast mixture will be erupted. This study has combined close investigation of the deposits of the 1990-1995 eruption of Unzen volcano, Japan and detailed laboratory investigations on samples of this eruption and other volcanoes. The field work intended to reveal the density distribution of samples from within the eruptive products. Although all samples already underwent one eruption, their physical state (e.g. crystallinity, porosity) mostly remained close to sub-surface pre-eruption conditions due to their high viscosity and accordingly allowed their usage for the analysis of the fragmentation behaviour. In that purpose, rapid decompression experiments that simulate volcanic eruptions triggered by internal gas overpressure have been performed at 850 °C to evaluate fragmentation threshold and fragmentation efficiency. Laboratory investigations of that kind are one approach to bridge the gap between observational field volcanology and risk assessment as they reveal information on what can not be investigated closely but what is essential to know for realistic eruption models and the adjacent hazard mitigation. Changing the experimental conditions and close investigation of the artificial products reveals the influence of physical properties on the fragmentation behaviour. The density distribution inside a dome and the upper part of the conduit is crucial to the eruptive style of an explosive volcano. This information cannot be collected during an ongoing eruption but is important for future hazard assessment via modelling conduit flow and dome collapse/explosion behaviour. Therefore, the percentage of the mass fractions of all rock types in the primary and secondary volcanic deposits must be evaluated. For this purpose and at the lowest logistic effort, field-based density measurements have been performed on Unzen volcano, Japan. The resultant density distribution was found to be generally bimodal at constant peak values but changing peak ratios. The most abundant rock types at Unzen exhibited an open porosity of 8 and 20 vol.%, respectively. The porosity was found to be arranged in layers of cm- to dm-scale that were oriented subparallel to flow direction, i.e. subvertical within the conduit and flank-parallel within the dome lobes. The achieved results allowed for an internal picture of the dome during the last eruption of Unzen volcano. The evaluated picture of the density distribution within the uppermost parts of the conduit and the dome itself allowed for insights into and a better understanding of magma ascent and degassing conditions at Unzen volcano during its last eruption. Knowledge of the density distribution is additionally required to draw conclusions from the results of laboratory investigations on the fragmentation behaviour to the monitored behaviour of Unzen volcano during its last eruption. In the laboratory, the fragmentation behaviour upon rapid decompression has been investigated in a modified fragmentation bomb (Spieler et al., 2004). At 850 °C, initial overpressure conditions as high as 50 MPa have been applied to sample cylinders (25 mm diameter, 60 mm length) drilled from natural samples. In a first step, the minimum overpressure required to cause complete sample fragmentation (= fragmentation threshold, ΔPfr) has been evaluated. Results from samples of several volcanoes (Unzen, Montserrat, Stromboli, and Mt. St. Helens) showed that ΔPfr mainly depended on open porosity and permeability of the specific sample as these parameters were controlling pressure build-up and loss. The experiments further revealed that sample fragmentation was not the result of a single process but the result of a combination of simultaneously occurring processes as indicated by Alidibirov et al. (2000). The degree of influence of a single process to the fragmentation behaviour was found to be porosity-dependent. Further experiments at initial pressure conditions above ΔPfr and close investigation of the artificially generated pyroclasts allowed evaluating the fragmentation efficiency upon changing physical properties of the used samples. The efficiency of sample size reduction was investigated by grain-size analysis (dry sieving for particles bigger than 0.25 mm and wet laser refraction for particles smaller than 0.25 mm) and surface area measurements (by Argon adsorption). Results of experiments with samples of different porosities at different initial pressure values showed that the efficiency of fragmentation increased with increasing energy. The energy available for fragmentation was estimated from the open porosity and the applied pressure. A series of abrasion experiments was performed to shed light on the grain size reduction due to particle-particle interaction during mass movements. The degree of abrasion was found to be primarily depending on porosity and experimental duration. The results showed that abrasion may change the density distribution of block-and-ash flows (BAF) by preferentially abrading porous clasts. However, during the short drying interval prior to the analysis of the experimental pyroclasts, abrasion-induced grain-size reduction only played a minor role and was assumed to be negligible.
References
Alidibirov M (1994) A model for viscous magma fragmentation during volcanic blasts. Bull
Volcanol 56, 459-465
Alidibirov M and Dingwell DB (1996) An experimental facility for investigation of magma
fragmentation by rapid decompression. Bull Volcanol 58, 411-416
Alidibirov M and Dingwell DB (2000) Three fragmentation mechanisms for highly viscous
magma under rapid decompression. JVGR 100, 413-421
Andronico D, Bertagnini A, Corsaro RA, Landi P, Miraglia L, Pompilio M (2003) Caratteri
mineralogico-petrografici dei prodotti emessi durante l’esplosione dello Stromboli del
5 aprile 2003. Preliminary report of INGV Catania
Avramov I (1994) Viscosity of undercooled melts. Journal of Materials Science letters 13,
1367-1369
Belikov BP, Zalesskii BV, Rozanov YA, Sanina EA, and Timchenko IP (1964) Methods of
studying the physicomechanical properties of rocks. In: Zalesskii BV (ed.) Physical
and mechanical properties of rocks. Izdatel’stvo Nauka, Moskau, 1-58
Botcharnikov R, Holtz F, Behrens H, and Sato H (2003) Phase equilibrium study and
constraints on pre-eruptive conditions of Unzen magmas. Abstract volume of IODPICDP
meeting 2003, Mainz, Germany
Cagnoli B, Barmin A, Melnik O, and Sparks RSJ (2002) Depressurization of fine powders
in a shock tube and dynamics of fragmented magma in volcanic conduits. EPSL 204,
101-113
Cas RAF and Wright JV (1987) Volcanic successions: modern and ancient. Chapman &
Hall, London Glasgow New York Tokyo Melbourne Madras, 476-478
Dingwell DB (1996) Volcanic dilemma: Blow or flow? Science 273, 1054-1055
Dingwell DB (1998) Recent experimental progress in the physical description of silicic
magma relevant to explosive volcanism. In: Gilbert JS and Sparks RSJ (eds.) The
physics of explosive volcanic eruptions. Geol.Soc., London, Spec. Pub., 145, 9-26
Gardner JE, Thomas RME, Jaupart C, and Tait S (1996) Fragmentation of magma during
Plinian volcanic eruptions. Bull Volcanol 58, 144-162
Hoblitt RP and Harmon RS (1993) Bimodal density distribution of cryptodome dacite from
the 1980 Mount St. Helens, Washington. Bull Volcanol 55, 421-437
Hoshizumi H, Uto K, and Watanabe K (1999) Geology and eruptive history of Unzen
volcano, Shimabara Peninsula, Kyushu, SW Japan. JVGR 89, 81-94
Reference list
99
Hoshizumi H, Uto K, Matsumoto A, and Kurihara A (2004) Growth history of Unzen
volcano, Kyushu, Japan – Results of two flank drillings of Unzen Scientific Drilling
Project. Abstract V24B-02, AGU Fall meeting
Houghton BF and Wilson CJN (1989) A vesicularity index for pyroclastic deposits. Bull
Volcanol 51, 451-462
Ichihara M, Rittel D, and Sturtevant B (2002) Fragmentation of a porous viscoelastic
material: Implications to magma fragmentation. J. Geophys. Res. 106, 2226-2239
Koptsik S, Strand L, and Clarke N (2003) On the calculation of the surface area of different
soil size fractions. Applied Geochemistry 18, 629-651
Kueppers U, Scheu B, Spieler O, Dingwell DB (2005) Field-based density measurements as
tool to identify pre-eruption dome structure: set-up and first results from Unzen
volcano, Japan. JVGR 141, 65-75.
Mader HM, Philips JC, Sparks RSJ, and Sturtevant B (1996) Dynamics of explosive
degassing of magma: observations of fragmenting two-phase flows. J. Geophys. Res.
101, 5547-5560
Mastrolorenzo G, Brachi L, and Canzanella A (2001) Vesicularity of various types of
pyroclastic deposits of Campi Flegrei volcanic field: evidence of analogies in magma
rise and vesiculation mechanisms. JVGR 109, 41-53
Mayfield JD and Schiffman P (1998) Measuring the density of porous volcanic rocks in the
field using a saran coating. Journal of geoscience education 46, 460-464
McBirney AR and Murase T (1970) Factors governing the formation of pyroclastic rocks.
Bull Volcanol 34, 372-384
Miyabuchi Y (1999) Deposits associated with the 1990-1995 eruption of Unzen volcano,
Japan. JVGR 89, 139-158
Mueller S, Spieler O, Scheu B, and Dingwell DB (2005) Permeability and degassing of
dome lavas undergoing rapid decompression: an experimental determination. Bull
Volcanol doi: 10.1007/s00445-004-0392-4
Mueller S, Spieler O, Kueppers U, Scheu B, and Dingwell DB (2005) Density Distribution
in Pyroclastic Deposits: A Comparative Study. Abstract at EGU meeting, Vienna,
Austria
Mungall JE (1995) Textural controls on explosivity of lava in Merapi-type block and ash
flows. Extended Abstract of IAVCEI meeting
Nakada S and Tanaka M (1991) Magmatic processes of Unzen volcano. Bulletin of the
Volcanological Society of Japan 36, 113-121
Reference list
100
Nakada S and Motomura Y (1999) Petrology of 1990-1995 eruption. JVGR 89, 173-196
Nakada S, Shimizu H, and Ohta K (1999) Overview of the 1990-1995 eruption at Unzen
volcano. JVGR 89, 1-22
Nakada S, Yoshimoto M, Shimano T, Kurokawa M, Nakai S, Sugimoto T, Hoshizumi H,
Oguri K, Noguchi S, and Goto Y (2004) Petrology of conduit lava at Unzen volcano;
results of Unzen Scientific Drilling Project. Abstract V33D-1491, AGU Fall meeting
Nonaka M, Nakada S, and Goto Y (2004) Emplacement process of the 1991-1995 dome at
Unzen volcano, Japan. Abstract V33D-1486, AGU Fall meeting
Okada H (1992) Geological and tectonic setting of Unzen volcano. In: Yanagi T, Okada H,
and Ohta K (eds.) Unzen volcano – the 1990-1992 eruption. The Nishinippon Kyushu
University Press, 1992
Papale P (1999) Strain-induced magma fragmentation in explosive eruptions. Nature 397
425-428
Polacci M, Pioli L, and Rosi M (2003) The plinian phase of the campanian ignimbrite
eruption (Phlegrean Fields, Italy): evidence from density measurements and textural
characterization of pumice. Bull Volcanol 65, 418-432
Raue H (2004) Magmenfragmentation im bruchhaften Regime: ein neues Modell zur
Energiebilanzierung am Beispiel der Phlegräischen Felder/Italien. PhD Thesis,
University of Würzburg, Germany
Richet P and Bottinga Y (1995) Rheology and configurational entalpy of silicate melts.
Reviews in Mineralogy 32, 67-93
Riley CM, Rose WI, and Bluth GJS (2003) Quantitative shape measurements of distal
volcanic ash. J. Geophys. Res. 108 (B10) 2504, doi:10.1029/2001JB000818
Romano C, Mungall J, Sharp T, and Dingwell DB (1996) Tensile strengths of hydrous
vesicular glasses: an experimental study. Am. Mineral. 81 (1996) 1148–1154
Sakuma S, Nakada S, and Uto K (2004) Unzen Scientific Drilling Project: Challenging
drilling operation into the magmatic conduit shortly after eruption. Abstract V24B-03,
AGU Fall meeting
Scheu B (2005) Understanding silicic volcanism: Constraints from elasticity and failure of
vesicular magma. PhD thesis, University of München, Germany
Schleyer R (1987) The goodness of fit to ideal Gauss and Rosin distributions: a new grainsize
parameter. J. Sed. Petrol. 57, 871-880
Reference list
101
Schopper JR (1982) Porosity and permeability. In: Angenheister G (ed) Numerical Data and
Functional Relationships in Science and Technology. Springer, Berlin Heidelberg
New York, 184-193
Schwarzkopf LM, Schmincke HU, and Troll VR (2001) Pseudotachylite on impact marks of
block surfaces in block-and-ash flows at Merapi volcano, Central Java, Indonesia.
Geol. Rundsch. 90, 769-775
Smith JV, Miyake Y, and Oikawa T (2001) Interpretation of porosity in dacite lava domes
as ductile-brittle failure textures. JVGR 112, 25–35
Sparks RSJ (1978) The dynamics of bubble formation and growth in magmas: a review and
analysis, JVGR 28, 257-274.
Sparks RSJ, Barclay J, Jaupart C, Mader HM, and Phillips JC (1994) Physical aspects of
magma degassing. I. Experimental and theoretical constraints on vesiculation, Rev.
Mineral. 30, 414-445
Spieler O (2001) Die Fragmentierung hochviskoser Magmen – Experimenteller Aufbau und
Analysetechniken, PhD thesis, University of Munich, Germany
Spieler O, Alidibirov M, and Dingwell DB (2003) Grain-size characteristics of experimental
pyroclasts of 1980 Mount St. Helens cryptodome dacite: effects of pressure drop and
temperature. Bull. Volcanol. 65, 90– 104.
Spieler O, Dingwell DB, and Alidibirov M (2004) Magma fragmentation speed: An
experimental determination. JVGR 129, 109-123.
Spieler O, Kennedy B, Kueppers U, Dingwell DB, Scheu B, and Taddeucci J (2004) The
fragmentation threshold of pyroclastic rocks. EPSL 226, 139-148
Taddeucci J, Spieler O, Ichihara M, Dingwell DB, and Scarlato P (2004) Vesiculation,
fragmentation, and degassing in a viscoelastic magma analogue. IAVCEI General
Assembly, Pucòn, Chile
Ui T, Matsuwo N, Suita M, and Fujinawa A (1999) Generation of block-and-ash flows
during the 1990-1995 eruption of Unzen Volcano, Japan. JVGR 89, 123-137
Umakoshi K, Shimizu H, Matsuwo N and Ohta K (1992) Surface temperature
measurements of lava domes and pyroclastic flows by infrared thermal video system.
In: Yanagi T, Okada H, and Ohta K (eds.) Unzen volcano – the 1990-1992 eruption.
The Nishinippon Kyushu University Press, 1992
Venezky DY and Rutherford MJ (1999) Petrology and Fe-Ti oxide reequilibration of the
1991 Mount Unzen mixed magma. JVGR 89, 213-230
Reference list
102
Watanabe K and Hoshizumi H (1995) Geological Map of Unzen volcano. Geological map
of volcanoes 8, Geological survey of Japan
Webb SL and Dingwell DB (1989) Structural relaxation in silicate melts and non-
Newtonian melt rheology in igneous processes. Physics and Chemistry of Minerals 16,
508-516
Woods AW, Sparks RSJ, Ritchie LJ, Batey J, Gladstone C, and Bursik MI (2002) The
explosive decompression of a pressurized volcanic dome: the 26 December 1997
collapse and explosion of Soufrière Hills Volcano, Montserrat. In: Druitt TH and
Kokelaar BP (eds.) The eruption of Soufrière Hills Volcano, Montserrat, from 1995 to
1999. Geological Society, London, Memoirs, 21, 595-602
Zhang Y (1999) A criterion for the fragmentation of bubbly magma based on brittle failure
theory. Nature 402, 648 – 650
Zimanowski B, Wohletz K, Dellino P, and Buettner R (2003) The volcanic ash problem.
JVGR 122, 1-5
---------------------------------------------------------------------------------------------------------------
Product Manual COULTER LS Series, Version 2.11a (August 1997)
Operator’s Manual Gemini III 2375 Surface Area Analyzer, Version 237-42825-01
(October 1996)
Volcanol 56, 459-465
Alidibirov M and Dingwell DB (1996) An experimental facility for investigation of magma
fragmentation by rapid decompression. Bull Volcanol 58, 411-416
Alidibirov M and Dingwell DB (2000) Three fragmentation mechanisms for highly viscous
magma under rapid decompression. JVGR 100, 413-421
Andronico D, Bertagnini A, Corsaro RA, Landi P, Miraglia L, Pompilio M (2003) Caratteri
mineralogico-petrografici dei prodotti emessi durante l’esplosione dello Stromboli del
5 aprile 2003. Preliminary report of INGV Catania
Avramov I (1994) Viscosity of undercooled melts. Journal of Materials Science letters 13,
1367-1369
Belikov BP, Zalesskii BV, Rozanov YA, Sanina EA, and Timchenko IP (1964) Methods of
studying the physicomechanical properties of rocks. In: Zalesskii BV (ed.) Physical
and mechanical properties of rocks. Izdatel’stvo Nauka, Moskau, 1-58
Botcharnikov R, Holtz F, Behrens H, and Sato H (2003) Phase equilibrium study and
constraints on pre-eruptive conditions of Unzen magmas. Abstract volume of IODPICDP
meeting 2003, Mainz, Germany
Cagnoli B, Barmin A, Melnik O, and Sparks RSJ (2002) Depressurization of fine powders
in a shock tube and dynamics of fragmented magma in volcanic conduits. EPSL 204,
101-113
Cas RAF and Wright JV (1987) Volcanic successions: modern and ancient. Chapman &
Hall, London Glasgow New York Tokyo Melbourne Madras, 476-478
Dingwell DB (1996) Volcanic dilemma: Blow or flow? Science 273, 1054-1055
Dingwell DB (1998) Recent experimental progress in the physical description of silicic
magma relevant to explosive volcanism. In: Gilbert JS and Sparks RSJ (eds.) The
physics of explosive volcanic eruptions. Geol.Soc., London, Spec. Pub., 145, 9-26
Gardner JE, Thomas RME, Jaupart C, and Tait S (1996) Fragmentation of magma during
Plinian volcanic eruptions. Bull Volcanol 58, 144-162
Hoblitt RP and Harmon RS (1993) Bimodal density distribution of cryptodome dacite from
the 1980 Mount St. Helens, Washington. Bull Volcanol 55, 421-437
Hoshizumi H, Uto K, and Watanabe K (1999) Geology and eruptive history of Unzen
volcano, Shimabara Peninsula, Kyushu, SW Japan. JVGR 89, 81-94
Reference list
99
Hoshizumi H, Uto K, Matsumoto A, and Kurihara A (2004) Growth history of Unzen
volcano, Kyushu, Japan – Results of two flank drillings of Unzen Scientific Drilling
Project. Abstract V24B-02, AGU Fall meeting
Houghton BF and Wilson CJN (1989) A vesicularity index for pyroclastic deposits. Bull
Volcanol 51, 451-462
Ichihara M, Rittel D, and Sturtevant B (2002) Fragmentation of a porous viscoelastic
material: Implications to magma fragmentation. J. Geophys. Res. 106, 2226-2239
Koptsik S, Strand L, and Clarke N (2003) On the calculation of the surface area of different
soil size fractions. Applied Geochemistry 18, 629-651
Kueppers U, Scheu B, Spieler O, Dingwell DB (2005) Field-based density measurements as
tool to identify pre-eruption dome structure: set-up and first results from Unzen
volcano, Japan. JVGR 141, 65-75.
Mader HM, Philips JC, Sparks RSJ, and Sturtevant B (1996) Dynamics of explosive
degassing of magma: observations of fragmenting two-phase flows. J. Geophys. Res.
101, 5547-5560
Mastrolorenzo G, Brachi L, and Canzanella A (2001) Vesicularity of various types of
pyroclastic deposits of Campi Flegrei volcanic field: evidence of analogies in magma
rise and vesiculation mechanisms. JVGR 109, 41-53
Mayfield JD and Schiffman P (1998) Measuring the density of porous volcanic rocks in the
field using a saran coating. Journal of geoscience education 46, 460-464
McBirney AR and Murase T (1970) Factors governing the formation of pyroclastic rocks.
Bull Volcanol 34, 372-384
Miyabuchi Y (1999) Deposits associated with the 1990-1995 eruption of Unzen volcano,
Japan. JVGR 89, 139-158
Mueller S, Spieler O, Scheu B, and Dingwell DB (2005) Permeability and degassing of
dome lavas undergoing rapid decompression: an experimental determination. Bull
Volcanol doi: 10.1007/s00445-004-0392-4
Mueller S, Spieler O, Kueppers U, Scheu B, and Dingwell DB (2005) Density Distribution
in Pyroclastic Deposits: A Comparative Study. Abstract at EGU meeting, Vienna,
Austria
Mungall JE (1995) Textural controls on explosivity of lava in Merapi-type block and ash
flows. Extended Abstract of IAVCEI meeting
Nakada S and Tanaka M (1991) Magmatic processes of Unzen volcano. Bulletin of the
Volcanological Society of Japan 36, 113-121
Reference list
100
Nakada S and Motomura Y (1999) Petrology of 1990-1995 eruption. JVGR 89, 173-196
Nakada S, Shimizu H, and Ohta K (1999) Overview of the 1990-1995 eruption at Unzen
volcano. JVGR 89, 1-22
Nakada S, Yoshimoto M, Shimano T, Kurokawa M, Nakai S, Sugimoto T, Hoshizumi H,
Oguri K, Noguchi S, and Goto Y (2004) Petrology of conduit lava at Unzen volcano;
results of Unzen Scientific Drilling Project. Abstract V33D-1491, AGU Fall meeting
Nonaka M, Nakada S, and Goto Y (2004) Emplacement process of the 1991-1995 dome at
Unzen volcano, Japan. Abstract V33D-1486, AGU Fall meeting
Okada H (1992) Geological and tectonic setting of Unzen volcano. In: Yanagi T, Okada H,
and Ohta K (eds.) Unzen volcano – the 1990-1992 eruption. The Nishinippon Kyushu
University Press, 1992
Papale P (1999) Strain-induced magma fragmentation in explosive eruptions. Nature 397
425-428
Polacci M, Pioli L, and Rosi M (2003) The plinian phase of the campanian ignimbrite
eruption (Phlegrean Fields, Italy): evidence from density measurements and textural
characterization of pumice. Bull Volcanol 65, 418-432
Raue H (2004) Magmenfragmentation im bruchhaften Regime: ein neues Modell zur
Energiebilanzierung am Beispiel der Phlegräischen Felder/Italien. PhD Thesis,
University of Würzburg, Germany
Richet P and Bottinga Y (1995) Rheology and configurational entalpy of silicate melts.
Reviews in Mineralogy 32, 67-93
Riley CM, Rose WI, and Bluth GJS (2003) Quantitative shape measurements of distal
volcanic ash. J. Geophys. Res. 108 (B10) 2504, doi:10.1029/2001JB000818
Romano C, Mungall J, Sharp T, and Dingwell DB (1996) Tensile strengths of hydrous
vesicular glasses: an experimental study. Am. Mineral. 81 (1996) 1148–1154
Sakuma S, Nakada S, and Uto K (2004) Unzen Scientific Drilling Project: Challenging
drilling operation into the magmatic conduit shortly after eruption. Abstract V24B-03,
AGU Fall meeting
Scheu B (2005) Understanding silicic volcanism: Constraints from elasticity and failure of
vesicular magma. PhD thesis, University of München, Germany
Schleyer R (1987) The goodness of fit to ideal Gauss and Rosin distributions: a new grainsize
parameter. J. Sed. Petrol. 57, 871-880
Reference list
101
Schopper JR (1982) Porosity and permeability. In: Angenheister G (ed) Numerical Data and
Functional Relationships in Science and Technology. Springer, Berlin Heidelberg
New York, 184-193
Schwarzkopf LM, Schmincke HU, and Troll VR (2001) Pseudotachylite on impact marks of
block surfaces in block-and-ash flows at Merapi volcano, Central Java, Indonesia.
Geol. Rundsch. 90, 769-775
Smith JV, Miyake Y, and Oikawa T (2001) Interpretation of porosity in dacite lava domes
as ductile-brittle failure textures. JVGR 112, 25–35
Sparks RSJ (1978) The dynamics of bubble formation and growth in magmas: a review and
analysis, JVGR 28, 257-274.
Sparks RSJ, Barclay J, Jaupart C, Mader HM, and Phillips JC (1994) Physical aspects of
magma degassing. I. Experimental and theoretical constraints on vesiculation, Rev.
Mineral. 30, 414-445
Spieler O (2001) Die Fragmentierung hochviskoser Magmen – Experimenteller Aufbau und
Analysetechniken, PhD thesis, University of Munich, Germany
Spieler O, Alidibirov M, and Dingwell DB (2003) Grain-size characteristics of experimental
pyroclasts of 1980 Mount St. Helens cryptodome dacite: effects of pressure drop and
temperature. Bull. Volcanol. 65, 90– 104.
Spieler O, Dingwell DB, and Alidibirov M (2004) Magma fragmentation speed: An
experimental determination. JVGR 129, 109-123.
Spieler O, Kennedy B, Kueppers U, Dingwell DB, Scheu B, and Taddeucci J (2004) The
fragmentation threshold of pyroclastic rocks. EPSL 226, 139-148
Taddeucci J, Spieler O, Ichihara M, Dingwell DB, and Scarlato P (2004) Vesiculation,
fragmentation, and degassing in a viscoelastic magma analogue. IAVCEI General
Assembly, Pucòn, Chile
Ui T, Matsuwo N, Suita M, and Fujinawa A (1999) Generation of block-and-ash flows
during the 1990-1995 eruption of Unzen Volcano, Japan. JVGR 89, 123-137
Umakoshi K, Shimizu H, Matsuwo N and Ohta K (1992) Surface temperature
measurements of lava domes and pyroclastic flows by infrared thermal video system.
In: Yanagi T, Okada H, and Ohta K (eds.) Unzen volcano – the 1990-1992 eruption.
The Nishinippon Kyushu University Press, 1992
Venezky DY and Rutherford MJ (1999) Petrology and Fe-Ti oxide reequilibration of the
1991 Mount Unzen mixed magma. JVGR 89, 213-230
Reference list
102
Watanabe K and Hoshizumi H (1995) Geological Map of Unzen volcano. Geological map
of volcanoes 8, Geological survey of Japan
Webb SL and Dingwell DB (1989) Structural relaxation in silicate melts and non-
Newtonian melt rheology in igneous processes. Physics and Chemistry of Minerals 16,
508-516
Woods AW, Sparks RSJ, Ritchie LJ, Batey J, Gladstone C, and Bursik MI (2002) The
explosive decompression of a pressurized volcanic dome: the 26 December 1997
collapse and explosion of Soufrière Hills Volcano, Montserrat. In: Druitt TH and
Kokelaar BP (eds.) The eruption of Soufrière Hills Volcano, Montserrat, from 1995 to
1999. Geological Society, London, Memoirs, 21, 595-602
Zhang Y (1999) A criterion for the fragmentation of bubbly magma based on brittle failure
theory. Nature 402, 648 – 650
Zimanowski B, Wohletz K, Dellino P, and Buettner R (2003) The volcanic ash problem.
JVGR 122, 1-5
---------------------------------------------------------------------------------------------------------------
Product Manual COULTER LS Series, Version 2.11a (August 1997)
Operator’s Manual Gemini III 2375 Surface Area Analyzer, Version 237-42825-01
(October 1996)
Type
thesis
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