This is the second paper in a two-part series examining numerical simulations of buoyancy-driven flow in the presence of large viscosity contrasts. In the first paper, we demonstrated that a combination of three numerical tools, an extended ghostfluid-type method, the level set approach, and the extension velocity technique accurately simulate complex interface dynamics in the presence of large...

Mt. Cameroon is one of the most active volcanoes in Africa and poses a possible threat to about half a million people in the area, yet knowledge of the volcano's underlying magma supply system is sparse. To characterize Mt. Cameroon's magma plumbing system, we employed mineral-melt equilibrium thermobarometry on the products of the volcano's two most recent eruptions of 1999 and 2000. Our resul...

Lunar floor-fractured craters (FFCs) represent the surface manifestation of a class of shallow crustal intrusions in which magma-filled cracks (dikes) rising to the surface from great depth encounter contrasts in host rock lithology (breccia lens, rigid solidified melt sheet) and intrude laterally to form a sill, laccolith or bysmalith, thereby uplifting and deforming the crater floor. Recent d...

Studies along the Mid-Atlantic Ridge (MAR) and East Pacific Rise (EPR) show that seamount abundance is a strong function of spreading rate. At the MAR, small axial seamounts are a dominant morphologic feature of the inner valley floor, while at the EPR seamounts are rarely observed within the neovolcanic zone. The Gala¤pagos Spreading Center (GSC) provides an excellent location to test the infl...

For a prescribed porosity, the coupled magma/mantle flow equations can be formulated as a two-field system of equations with velocity and pressure as unknowns. Previous work has shown that while optimal preconditioners for the two-field formulation can be obtained, the construction of preconditioners that are uniform with respect to model parameters is difficult. This limits the applicability o...

Geochemical modeling of magma mixing allows for evaluation of volumes of magma storage reservoirs and magma plumbing configurations. A new analytical expression is derived for a simple two-component box-mixing model describing the proportions of mixing components in erupted lavas as a function of time. Four versions of this model are applied to a mixing trend spanning episodes 3–31 of Kilauea V...

Introduction In the following chapters we will find that nearly all of the varied aspects of volcanism are either directly or indirectly controlled by the chemical composition of magma and the rate at which it cools and solidifies. If you are to understand and appreciate subsequent discussions of volcanoes and related volcanic phenomena, it is essential that you have a good grasp of the basic c...

During volcanic eruptions, measurements of the rate at which magma is erupted underpin hazard assessments. For eruptions dominated by the effusion of lava, estimates are often made using satellite data; here, in a case study at Mount Etna (Sicily), we make the first measurements based on terrestrial laser scanning (TLS), and we also include explosive products. During the study period (17–21 Jul...

Initially homogeneous uspensions of bubbles in basaltic magmas and lava flows may become unstable and form rising waves or layers of bubbles. We derive a set of model equations for the two-phase (bubble-liquid) system and present the results of a linear stability analysis and numerical simulations. Periodic vesicle layers are preserved in Columbia l•iver flows with a spacing of •1 m; the predic...

Ž . Gabbroic sills intruding dunite in the crust–mantle transition zone MTZ of the Oman ophiolite have textures and compositions very similar to those in modally layered gabbros that form the lower part of the gabbro section in the ophiolite, and different from those in non-layered gabbros near the dike–gabbro transition. The presence of gabbroic sills in the MTZ indicates that modally layered ...