12,000

We have over 12,000 students, from over 100 countries, within one of the safest campuses in the UK

93%

93% of Lancaster students go into work or further study within six months of graduating

Home > Research > Publications & Outputs > Dome-building eruptions : insights from analogu...
View graph of relations

« Back

Dome-building eruptions : insights from analogue experiments.

Research output: Contribution to journalJournal article

Published

Journal publication date7/11/2008
JournalGeological Society Special Publications
Journal number1
Volume307
Number of pages31
Pages207-237
Original languageEnglish

Abstract

Laboratory flows, self-capped by high-viscosity fluid, exhibit vertical pressure gradients similar to those postulated within conduits feeding dome-building eruptions. Overpressure and pressure cycles exhibited at laboratory scale provide insight into the mechanism of tilt cycles at volcanic scale. Experimental pressure cycles correlated with the rate of gas escape, with pressure rise being controlled by diffusion of volatile into bubbles during times when gas escape from the flow was negligible. The increase in pressure continued until margin decrepitation created preferential pathways for rapid gas escape from permeable foam, thereby reducing pressure within the flow. As pressure reduced, the gas escape pathways sealed and diffusion repressurized the system. This implies that tilt cycles, such as those exhibited by the Soufrie`re Hills Volcano, Montserrat, result from a diffusively pumped process that oscillates around the viscous-elastic transition within the outer regions of the flow. Phases of open- and closedsystem degassing result, with gas escaping through fractures created and maintained by the flow process itself. Fluid-dynamically, this mechanism generates an oscillation between Poiseuille flow and plug flow, with a 1-D model of plug motion giving a reasonable representation of observation in both experimental and volcanic cases.