Field measurements of the rheology of lava

KNOWLEDGE of magma rheology is required to understand many igneous and volcanic processes. Viscosities of silicate melts can be estimated from their chemical composition and temperature using empirical methods1–3. However, the validity of these estimates has been established only at supraliquidus temperatures where common igneous melts behave as newtonian fluids. Recent experimental evidence from field and laboratory studies4–7, has demonstrated that, at subliquidus temperatures, some magmas behave as non-newtonian fluids due to the presence of dispersed crystals and gas bubbles and possibly as a consequence of structuring in the silicate melt. We present data here on the rheological properties of small lava flows which were erupted on Mount Etna in 1975. These data were obtained by field measurements using a new field viscometer8, a shear vane attached to a torque wrench, a conventional penetrometer and various field techniques for estimating rheological properties from the dimensions of lava flows.

[1]  R. Sparks,et al.  The transport of xenoliths in magmas , 1977 .

[2]  D. L. Peck,et al.  The viscosity of basaltic magma; an analysis of field measurements in Makaopuhi lava lake, Hawaii , 1968 .

[3]  G. R. ROBSON,et al.  Thickness of Etnean Lavas , 1967, Nature.

[4]  Y. Bottinga,et al.  The viscosity of magmatic silicate liquids; a model calculation , 1972 .

[5]  G. Hulme,et al.  The Interpretation of Lava Flow Morphology , 1974 .

[6]  C. M. Scarfe,et al.  Viscosity of Basic Magmas at Varying Pressure , 1973 .

[7]  H. R. Shaw.  Viscosities of magmatic silicate liquids; an empirical method of prediction , 1972 .

[8]  A. Philpotts.  Density, surface tension and viscosity of the immiscible phase in a basic, alkaline magma , 1972 .

[9]  Ralph O. Kehle,et al.  Physical Processes in Geology , 1972 .

[10]  R. S. J. Sparks,et al.  Effect of degassing on rheology of basaltic lava , 1978, Nature.

[11]  M. L. Sbar,et al.  Premonitory Changes in Seismic Velocities and Prediction of Earthquakes , 1973, Nature.

[12]  H. N. Stein,et al.  Deviations from Newtonian rheological behavior in alkali borate glasses , 1969 .

[13]  Herbert R. Shaw,et al.  Comments on viscosity, crystal settling, and convection in granitic magmas , 1965 .

[14]  Herbert R. Shaw,et al.  Rheology of Basalt in the Melting Range , 1969 .

[15]  S. Self,et al.  Mount Etna and the 1971 eruption - Rheological features of the 1971 Mount Etna lavas , 1973, Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences.

[16]  A. McBirney,et al.  Properties of some common igneous rocks and their melts at high temperatures , 1973 .

[17]  R. Sparks,et al.  Classification and formation of lava levees on Mount Etna, Sicily , 1976 .

[18]  G. A. Macdonald.  PHYSICAL PROPERTIES OF ERUPTING HAWAIIAN MAGMAS , 1963 .