Magma fragmentation dynamics: experiments with analogue porous low-strength material |
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| Authors: | Mikhail Alidibirov Vsevolod Panov |
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| Institution: | Bayerisches Geoinstitut, Universit?t Bayreuth, D-95440 Bayreuth, Germany, DE
Institute of Volcanic Geology and Geochemistry, Russian Academy of Sciences, 683006 Petropavlovsk-Kamchatsky, Russia, RU
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| Abstract: | Experiments were conducted on the fragmentation of analogue low-strength porous material (plastiprin) by rapid decompression
in a shock-tube-type apparatus. The porous samples (length=365 mm, cross-section dimensions 40×40 mm) pressurized by air to
pressures up to 0.9 MPa, were rapidly decompressed to 0.1 MPa. Rapid decompression of samples caused fragmentation and ejection
of the fragmentation products into a large volume tank. The process of analogue material fragmentation was documented using
high-speed cinematography and dynamic pressure measurements. The duration of the fragmentation event is significantly shorter
than that of the ejection event. The fragmentation of material precedes the acceleration of fragments. As a result of fragmentation,
sub-parallel fractures are generated. The characteristic fragment size decreases as the initial pressure differential increases.
The ejected fragments obtain velocities of 60 m/s. The mechanisms of material fragmentation during unloading and fragmentation
wave propagation are discussed. The experimental results provide insight into the fragmentation dynamics of highly viscous
magmas in which brittle failure at high strain rate is possible.
Received: 23 July 1997 / Accepted: 23 November 1997 |
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| Keywords: | Fragmentation Decompression Magma Experimental Volcanic Explosion Eruption |
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