The mechanical conditions for a volcanic eruption to occur are conceptually simple: a magma-driven fracture (normally a dyke) must be able to propagate from the source to the surface. The mechanics of small to moderate (eruptive volumes less than 10 km 3 ) is reasonably well understood, whereas that of large eruptions (eruptive volumes of 10-1000 km 3 ) is poorly understood. Here I propose that...

there are three different basic dykes in the northeast of golpayegan area, central part of sanandaj-sirjan zone (ssz) including: mylonitic gabbros (group 1), alkali dioritic-basanitic dykes (group 2) and alkali monzogabbroic to monzodioritic dykes (group 3). group 2 and 3 cut post-collisional rocks and are related to after subduction processes of neo-tethys. geochemistry characteristic of studi...

[1] Starting soon after the 1997 eruption at Okmok volcano and continuing until the start of the 2008 eruption, magma accumulated in a storage zone centered ∼3.5 km beneath the caldera floor at a rate that varied with time. A Mogi‐type point pressure source or finite sphere with a radius of 1 km provides an adequate fit to the deformation field portrayed in time‐sequential interferometric synth...

Volcanic ash is fragments of magma, and consists of minerals and volcanic glass. These materials in the ash can provide important information on the nature of the magma, because chemical compositions of magma usually show distinct features in each volcano, and because assemblages and compositions of minerals reflect their host melt. Using assemblages and chemical compositions of minerals and gl...

Regulatory sites that control gene expression are essential to the proper functioning of cells, and identifying them is critical for modeling regulatory networks. We have developed Magma (Multiple Aligner of Genomic Multiple Alignments), a software tool for multiple species, multiple gene motif discovery. Magma identifies putative regulatory sites that are conserved across multiple species and ...

Ground deformation often precedes volcanic eruptions, and results from complex interactions between source processes and the thermomechanical behaviour of surrounding rocks. Previous models aiming to constrain source processes were unable to include realistic mechanical and thermal rock properties, and the role of thermomechanical heterogeneity in magma accumulation was unclear. Here we show ho...

Numerical models show that maximum dike width at oceanic spreading centers should scale with axial lithospheric thickness if the pre-diking horizontal stress is close to the Andersonian normal faulting stress and the stress is fully released in one dike intrusion. Dikes at slow-spreading ridges could be over 5 m wide and maximum dike width should decrease with increasing plate spreading rate. H...

Introduction: Defining the mineralogy and composition of martian mantle source regions has proved to be a difficult task because: (1) the martian sample set does not include samples of the mantle, and (2) many of the samples are either cumulates or are highly fractionated and therefore not in equilibrium with the mantle. Despite these complexities, isotopic evidence suggests that Mars had a mag...

The Indian Peak volcanic field is representative of the more than 50,000 km3 of ashflow tuff and tens of calderas in the Great Basin that formed during the Oligocene-early Miocene "ignimbrite flareup" in southwestern North America. The field formed about 32 to 27 Ma in the southeastern Great Basin and consists of the centrally positioned I n d i Peak caldera complex and a surrounding blanket of...

A model for the origin, ascent, and eruption of the lunar A17 orange glass magma has been constructed using petrological constraints from gas solubility experiments and from analyses of the lunar sample 74220 to better determine the nature and origin of this unique explosive eruption. Three stages of the eruption have been identified. Stage 1 of the eruption model extends from ~550 km, the A17 ...