Abstract Simple experiments have been conducted to study the strain evolution in lava dome cross sections. A viscous fluid is injected vertically from a reservoir in- to a feeding conduit. Silicone putty is used as analogue magma. Two-dimensional experiments allow the assess- ment of the internal strain within the dome. Particle paths are symmetrical on either side of a central line passing through the feeding conduit and display para- bolic trajectories. The highest strain zone is located above the extrusion zone. In cross sections, stretch tra- jectories show a remarkable concentric pattern, wrapping around the extrusion zone of the analogue magma. To the lateral margins, a triple junction of stretch trajecto- ries defines an isotropic point in the strain field. In the main central part of the dome, an intermediate zone of reversed sense of shearing is caused by a change in the sign of the velocity gradient with respect to that in the upper and lower zones. Knowledge of this evolving strain pattern can provide a better understanding of the evolution of natural domes. Also, it can help to unravel the kinematic history of ancient domes partly removed by erosion. Keywords Analogue modelling · Domes emplacement · Kinematic evolution · Particle paths · Stretch trajectories Introduction Studies of dome growth are abundant (e.g. Williams 1932; Christiansen and Lipman 1966; Cole 1970; Huppert et al. 1982; Murase et al. 1985; Fink and Manley 1987; Swanson et al. 1987; Anderson and Fink 1990; Duffield and Dalrymple 1990; Swanson and Holcomb 1990; Dadd 1992; Miller 1994; Fink and Bridges 1995; Nakada et al. 1995). These mostly deal with the mechanical aspects of lava dome emplacement. These studies have brought much information about the evolution of height vs. diameter, flow vs. extrusion rate, and the rheology of the magma during emplacement, which constitute an invaluable source of data. Huppert et al. (1982) were the first to present ana- logue models concerning lava dome growth. They used a simple Newtonian fluid flowing radially under its own hydrostatic pressure on a horizontal surface. They compared experimental results with the growth of the St Vincent Soufriere dome. Over the past decade, several studies have described experiments of lava domes. Blake (1990) introduced non-Newtonian effects using Bingham slurries of kaolin and water. According to observed changes in aspect ratios, Blake proposed four classes of domes: upheaved plugs, pelean, low and coulee. Experiments using kaolin slurry injected in to cold water (Griffiths and Fink 1993, 1997) or gum resin (Lejeune 1995) have allowed a better understanding of the cooling effect on lava dome evolution. Fink and Bridges (1995) emplaced polyethylene glycol (PEG) wax into cold sucrose to study the impact of eruption history and cool- ing rate on lava dome growth. These studies have dealt with the geometrical aspects of domes, including the evo- lution of the height/diameter ratio with time and the vary- ing textures at the surface of the dome during cooling. They have stressed the physical constraints leading to dome collapse and explosion, and have investigated their consequences on the dynamics of eruptive processes. Field data on the evolving strain within endogenous lava domes are scarce. This is mainly for two reasons: Editorial responsibility: D. Dingwell C. Buisson ( ✉ ) Laboratoire Magmas et Volcans, Observatoire de Physique du Globe, CNRS – Université Blaise Pascal, 5 rue Kessler, 63038 Clermont-Ferrand, France e-mail: C.Buisson@opgc.univ-bpclermont.fr e-mail: cecile.buisson@laposte.net Tel.: +33-4-73346721, Fax: +33-4-73346744 O. Merle Laboratoire Magmas et Volcans, Observatoire de Physique du Globe, CNRS – Université Blaise Pascal, 5 rue Kessler, 63038 Clermont-Ferrand, France Bull Volcanol (2002) 64:363–371 DOI 10.1007/s00445-002-0213-6 RESEARCH ARTICLE C. Buisson · O. Merle Experiments on internal strain in lava dome cross sections Received: 9 March 2001 / Accepted: 8 March 2002 / Published online: 18 June 2002 © Springer-Verlag 2002