3. types of eruption - tu bergakademie freiberg€¦ · 3. types of eruption christoph breitkreuz,...
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3. Types of eruptionChristoph Breitkreuz,
TU Bergakademie Freiberg
Fig. 2.2 Schematic diagram of a explosive volcanic system showingdifferent regions and rheologicalregimes from non-vesiculated magmato eruption plume. (From Fisher & Schminke 1984, after Wilson et al., 1980).
Fig. 2.4 A schematic volcanic eruption column, showing the variation of velocity with height and relative importance of buoyancy and momentum. Buoyancy carries column to height HB; lateral spreading takes place above HB. Momentum drivessome material upwards to a maximum height HT(Orton 1996, from Self & Walker, 1994).
Magmatic fragmentation: byexpansion of vesicles and high deformation rate
Magmatic-phreatomagmatic-phreatic
after Walker 1973
after Pyle 1989
Bc = distance of“MPS/2“
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Fissure eruption
Hawaiian Eruption:- low-viscosity, SiO2-poor magma- Lava fontains- Crater lava lakes- extended lava fields
Strombolian eruption: Etna, Boris Behnke
Southern Vent, 2002
- Medium-viscosity SiO2-poor magma (phenocrysts + microlith!)
Encyclop. Volc 1999
Etna (Photo K. Berg)
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Evolution of an intra-plate volcanic field: Springerville Volcanic Field, AZ (Condit & Connor 1996)
Plinian eruption:- high-viscosity magma- volatile-rich- high magma eruption rate(many weeks)
Pinatubo 1991Mt. St. Helens, 1980
Vulcanian eruption: Fossa on Vulcano 1888-90e.g. Santiaguito, Guatemala
J. Lyons, MTU
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Soufriere Hills, oct. 1997, p-flow
Typical vulcanian eruptions:- short (< 120 sec.) eruptions (canon shot-like sound)- differentiated magma, moderate volatile content- low magma eruption rate
2002
e.g. Soufriere Hills (Montserrat): 4.8. - 21.10.1997 88 vulcanian eruptions;ballistic bombs (up to 1 m) Up to 1,7 km distance,2/3 p-flows, 1/3 fallout
Druitt et al. 2002
Morrissey & Mastin 1999(Encycl. Volc.)
Transition between vulcanian eruptions and those related to lava dome failure
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1966
Phreatomagmatic eruptions:
Surtsey 1963-64
Ukinrek, Alaska, 1977:Maar-forming eruptions(USGS + Lorenz)
Ruhapehu, NZ
Phreatomagmatic eruptions:- Magma – water interaction
(groundwater, ice, lake, sea)- high F, low D, relatively cool- Fragmentation processes:
among others „true“ explosions (according to physical definition) >>>
Leidenfrost film
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Physikalisch Vulkanologisches LaborUniversität Würzburg
Spark-flash camera at 0.1 Mframes/sec
Polished steel cylinder, 7.5 cm in diameter at 350 °CWater temperature of 85 °C
vapor film collapse induced by shock-wave passage at stable film boiling conditions
Stable film boiling (1 – 4 mm): reduced heat transfer
Physikalisch Vulkanologisches LaborUniversität Würzburg
Spark-flash camera at 0.1 Mframes/sec
Polished steel cylinder, 7.5 cm in diameter at 350 °CWater temperature of 85 °C
...after about 1.1 ms...
Zimanowski et al. 2004, U Würzburg
Well-known and feared in industrial plants:FCI = Fuel-Coolant-Interaction
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Physikalisch Vulkanologisches LaborUniversität Würzburg
HiCam 2, 10 Kframes/secAir gun bullet
Transparent carbonate melt
Physikalisch Vulkanologisches LaborUniversität Würzburg
experiments02
HiCam 2, 10 Kframes/sec
Processes in a surtseyan vent
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Another phreatomagmatic process:
Englacial volcanism
2-11-2004Grimsvötn, Iceland
Phreatic activity:
Magma / Lava / or pyroclastic flowdeposits provideheat for phreatic eruptions
Prior to the large eruption of May, 18th, 1980:Rising magma caused boiling and phreatic eruption of groundwater:
(USGS)Mt. St. Helens
Fig. 2.6 Interrelations of explosive energy, water-magma ratio, style of volcanic activity and volcaniclastic fragments in basaltichydrovolcanic eruptions (largely after Wohletz & Sheridan, 1983). The smallest fragments are produced in Taalian eruptions whenmost thermal energy is transferred to mechanical energy. The shape of shards produced (1-5) depends on the viscosity of the magmaand its degree of vesiculation: blocky shards (1) of poorly vesicular magma are most common; irregular, globular and spherical shards(2-4) indicate fluidal melts; platy and cuspate shards are part of vesicle walls and develop if vesiculated, generally more viscous magmainteracts with water. Non-explosive quench fragmentation can occur in any environment. For instance, views of hyaloclastites are fromthe Mid-Atlantic ridge (Schmincke et al., 1978) and a Permian example where lava flowed over unconsolidated nearshore marinesediments (From Orton 1996).
Water / magma -ratio and type of fragmention