clinopyroxene phenocrysts and microphenocrysts in potassic and sodic eosen alkaline volcanic rocks from the northern lahrud (nw iran) record various stages in the crystallization and evolution history of the alkaline melt as well as its origin. the rock series hosting the clinopyroxene phenocrysts is phonolitic tephrite and tephritic phonolite composition. theses rocks generally show porphyriti...

A summit and upper flank eruption occurred at Nyamulagira volcano, Democratic Republic of Congo, from 2–27 January 2010. Eruptions at Nyamulagira during 1996–2010 occurred from eruptive fissures on the upper flanks or within the summit caldera and were distributed along the ~N155E rift zone, whereas the 2011–2012 eruption occurred ~12 km ENE of the summit. 3D numerical modeling of Interferometr...

Oscillations of magma in volcanic conduits are thought to be the source of certain seismic and infrasonic signals observed near active volcanoes. However, the multiphase and stratified nature of magma within the conduit complicates the calculation of resonant modes that is required to interpret observations. Here we present a linearized mathematical framework to describe small-amplitude oscilla...

Products of voluminous pyroclastic eruptions with eruptive draw-down of several kilometers provide a snap-shot view of batholith-scale magma chambers, and quench pre-eruptive isotopic fractionations (i.e., temperatures) between minerals. We report analyses of oxygen isotope ratio in individual quartz phenocrysts and concentrates of magnetite, pyroxene, and zircon from individual pumice clasts o...

[1] A recent prospective on the Yellowstone Caldera discounts its explosive potential based on inferences from tomographic studies which suggests a high degree of crystallization of the underlying magma body. In this study, we show that many of the first teleseismic P-wave arrivals observed at seismic stations on the edge of the caldera did not travel through the magma body but have taken longe...

To the Editor — Detailed analysis of volcanic materials1 allows the study of eruptions that have not been witnessed directly. Rotella et al.2 undertake the challenge of interpreting submarine volcaniclastic deposits around Macauley Volcano, part of the Kermadec Arc in the southwest Pacific Ocean. They propose a ‘Tangaroan’ eruption style, based on the textural characteristics of dredged pumice ...

These notes survey some basic results in toric varieties over a field F , with examples and applications. A computer algebra package (written by the author) is described which deals with both affine and projective toric varieties in any number of dimensions (written in both MAGMA [MAGMA] and GAP [GAP]). Among other things, the package implements the desingularization procedure, constructs some ...

[1] Volcanic SO2 can affect the Earth’s environment. Where no direct measurements of SO2 in the atmosphere are available, a petrologic method of assessing sulfur release from the magma must be used. However, in studies of arcderived eruptions, satellite-based measurements of SO2 emissions using Total Ozone Mapping Spectrometer (TOMS) data are orders of magnitude greater than those calculated pe...