[1] Ground surface displacement (GSD) in large calderas is often interpreted as resulting from magma intrusion at depth. Recent advances in geodetic measurements of GSD, notably interferometric synthetic aperture radar, reveal complex and multifaceted deformation patterns that often require complex source models to explain the observed GSD. Although hydrothermal fluids have been discussed as a ...

[1] A generalized constitutive equation for bubbly liquids is presented which successfully reproduces the expected viscosity response for both steady flows with varying capillary number Ca (a measure of the bubble deformation) and unsteady flows with varying dynamic capillary number Cd (a measure of the steadiness of the flow) previously given in separate studies. The constitutive equation is g...

The Galileo spacecraft has been periodically monitoring volcanic activity on Io since June 1996, making it possible to chart the evolution of individual eruptions. We present results of coanalysis of Near-Infrared Mapping Spectrometer (NIMS) and solidstate imaging (SSI) data of eruptions at Pele and Pillan, especially from a particularly illuminating data set consisting of mutually constraining...

Magma degassing plays a fundamental role in controlling the style of volcanic eruptions. Whether a volcanic eruption is explosive, or effusive, is of crucial importance to approximately 500 million people living in the shadow of hazardous volcanoes worldwide. Studies of how gases exsolve and separate from magma prior to and during eruptions have been given new impetus by the emergence of more a...

S U M M A R Y Many unresolved questions in geodynamics revolve around the physical behaviour of the two-phase system of a silicate melt percolating through and interacting with a tectonically deforming host rock. Well-accepted equations exist to describe the physics of such systems and several previous studies have successfully implemented various forms of these equations in numerical models. T...

Introduction: Io, the innermost of the Galilean satellites, is the most volcanically active body in our solar system. While its volcanic eruptions can be studied directly, our knowledge of the underlying magmatic processes rests wholly on indirect inferences. Here we combine constraints from magma ascent and crustal density models to gain insight into the plumbing system underlying the Promethe...

[1] Observations of volcanoes extruding andesitic lava to produce lava domes often reveal cyclic behavior. At Soufrière Hills Volcano, Montserrat, cycles with subdaily and multiweek periods have been recognized on many occasions. Observations clearly show that the period of subdaily cycles is modulated by the multiweek cycle. The subdaily and multiweek cycles have been modeled separately as sti...

Multi-element abundances in twenty-four samples from the Serra Geral continental flood basalt system (Parana Basin) were determined by INAA to assess the trace element signature of primary magmatric sources. Isotopic Sr and Nd data were obtained on a 24-sample composite and three individual samples of the suite to constrain the influences of older enriched material. Twenty basaltic samples have...

The style and evolution of volcanic eruptions are dictated by the fluid mechanics governing magma ascent. Decompression during ascent causes dissolved volatile species, such as water and carbon dioxide, to exsolve from the melt to form bubbles, thus providing a driving force for the eruption. Ascent is influenced not only by the nucleation and growth of gas bubbles, but also magma rheology and ...

The Bushveld Complex formed by the crystallization of successive basaltic magmatism may be of the order of several million years. For example, the Columbia River Basalts (Hooper, injections of magma, which were sufficiently closely spaced in time that each previous magma had not cooled and differentiated 1988) were erupted in the period 17–12 Ma, with minor eruptions for a further 5 my, althoug...