Effects of gas escape and crystallization on the complexity of conduit flow dynamics during lava dome eruptions

• Published in: Journal of Geophysical Research: Solid Earth 2012-08, Vol.117 (B8), p.n/a
• Main Authors: Kozono, T., Koyaguchi, T.
• Format: Article
• Language: English
• Subjects: conduit flow model; Crystallization; Earth sciences; Earth, ocean, space; effect of crystallization on viscosity; Exact sciences and technology; Flow rates; Geophysics; Lava; lava dome eruption; Lava domes; Magma; Permeability; Porosity; transition to explosive eruption; vertical and lateral gas escapes; Volcanic eruptions; Volcanic gases; Volcanoes
• ISSN: 0148-0227; 2169-9313; 2156-2202; 2169-9356
• DOI: 10.1029/2012JB009343

We investigated the coupled effects of gas escape and crystallization on the dynamics of lava dome eruptions using a one‐dimensional conduit flow model. The relationship between chamber pressure pch and mass flow rate q for steady conduit flow commonly has a regime of negative differential resistance (i.e., dpch/dq < 0), which causes a transition from lava dome to explosive eruption. Two positive‐feedback mechanisms that result in negative differential resistance have been identified. First, effective magma viscosity decreases with increasing q because of a delay of crystallization, leading to reduced viscous wall friction (feedback 1). Second, magma porosity increases with increasing q because of less efficient gas escape, leading to reduced gravitational load (feedback 2). For high‐phenocryst‐content magma (volume fraction >0.5), feedback 1 is the main mechanism that forms negative differential resistance. In this case, the transition from lava dome to explosive eruption occurs when the magma supply rate exceeds a fixed critical value. For low‐phenocryst‐content magma (volume fraction