Showing papers in "Journal of Volcanology and Geothermal Research in 1998"

TL;DR: The field occurrence, age, classification and geochemistry of the Mesozoic volcanic rocks of Patagonia and West Antarctica are reviewed, using published and new information in this paper, where a diachronism is recognized between the Early-Middle Jurassic volcanism of eastern Patagonian (Marifil and Chon Aike formations) and the Middle Jurassic-earliest Cretaceous volcanisms of the Andean Cordillera (El Quemado, Ibanez and Tobifera formations).

TL;DR: In this article, the authors developed a general formulation for stereological analysis of particle distributions which is applicable to any particle size or size distribution (not limited to log-normal, unimodal, etc.).

TL;DR: In this article, it was shown that major changes in thinning rate occur as the particle size decreases with distance from the vent, as a consequence of the change of settling behavior from high to low Reynolds number as predicted by W.I. Rose.

TL;DR: A detailed study of the volcanic stratigraphy of the Erzurum-Kars plateau, together with new K-Ar ages and several hundred new major and trace-element analyses in order to evaluate the magmatic evolution of the plateau and its links to collision-related tectonic processes is presented in this paper.

TL;DR: In this paper, the authors used trace element data to identify distinct geochemical groups and evaluate the role of differentiation processes in the discovery of low-Ti basalts in the Afro-Arabian CFB province.

TL;DR: In this paper, the effects of bubble deformation, volume fraction, and shear rate on the rheology of bubble-bearing suspensions are investigated through a series of three-dimensional boundary integral calculations.

TL;DR: The major Quaternary volcanic centres are Ararat, Tendurek, Suphan and Nemrut as mentioned in this paper, which form significant peaks above the Turkish-Iranian high plateau.

TL;DR: In this paper, the authors show that pumice, scoria, and lava (150 samples) exhibit major and trace-element gradients as a function of SiO2 (58.9-47.2 wt%) and MgO (0-7.8 wt%); Mg# values are 10 with decreasing age for the Vesuvius system as a whole.

TL;DR: In this paper, a volcanic ash tracking model referred to as PUFF was developed to simulate the movement of airborne ash in near real-time following an eruption for the purposes of hazard warning.

TL;DR: In this article, the interplinian events at Somma-vesuvius were reconstructed using new data from twenty stratigraphic sections around the lower flanks of the volcano, and three main eruptions have been identified for the protohistoric period (3550 yr B.C. and A.D. 79).

TL;DR: In this article, 40 K-Ar and 40 Ar / 39 Ar isotopic ages from the northern Main Ethiopian Rift (MER)-southern Afar transition zone provide insights into the volcano-tectonic evolution of this portion of the East African Rift system.

TL;DR: The Torfajokull central volcano in south-central Iceland contains the largest volume of exposed silicic extrusives in Iceland (∼225 km^3) as mentioned in this paper.

TL;DR: In this paper, the effects of pyroclastic flows and surges on buildings, infrastructure elements, and to some extent on vehicles were investigated. But the authors focused on the effects on buildings and infrastructure elements and not on vehicles.

TL;DR: In Cappadocia (Central Anatolia, Turkey), high-K calc-alkaline volcanic rocks have a volume of at least 1000 km3 and cover an area of about 40,000 km2 as discussed by the authors.

TL;DR: The pit craters typically stoping over an underlying large-aperture rift zone fracture, and not by piston-like collapse over broad magma bodies or voids.

TL;DR: Neri et al. as discussed by the authors investigated the role of anhydrous magma composition, water content, and crystal content on the dynamics of explosive eruptions by modeling the ascent of magma along volcanic conduits and the subsequent pyroclastic dispersion in the atmosphere, described in a companion paper.

TL;DR: The Active Tracer High Resolution Atmospheric Model (ATHAM) as mentioned in this paper was designed to simulate explosive volcanic eruptions for a given mass flux of pyroclastic material under realistic atmospheric background conditions, and the model's equations are simplified such that, besides equations for gaseous, liquid and solid constituents of arbitrary concentrations, only the volume means of momentum and heat are predicted.

TL;DR: The results of an integrated electrical and electromagnetic survey in the active volcanic area of Mount Somma-Vesuvius (Naples, Italy) were presented and discussed in this paper.

TL;DR: The Mount Kozak igneous complex is located close to the towns of Ayvalik, Bergama and Burhaniye in the Western Anatolia, Turkey as discussed by the authors, and is represented by a high-K, calc-alkaline suite of predominantly intermediate and acidic composition.

TL;DR: In this article, the role of ductile layer thickness and viscosity on the deformation of a volcano was investigated using numerical finite-element modeling, and it was shown that lower viscosities in the ductile layers (low Πb) lead to faster rates of movement, and also affect the volcanic deformation style.

TL;DR: In this paper, unspiked K-Ar ages of Cumbre Vieja volcano in the Canary islands were measured from 20 samples from two series of cliff-forming and scree-forming series.

TL;DR: In this paper, the authors used Synthetic Aperture Radar (SAR) images of the European Remote Sensing (ERS) satellite and Digital Elevation Models (DEMs), complemented by field structural analysis, to understand the relationship between tectonics and volcanism in Central Anatolia.

TL;DR: In this paper, the authors collected volcanic gases and aerosols at Mt. Etna volcano over a long period (1991-1995) and measured their chemical composition by ICP-MS, showing that the alkali metals fractionate systematically within their family as they cross the melt-vapour interface, the heavier members being always more enriched than the lighter ones in aerosols.

TL;DR: In this paper, the distribution of polygenetic and monogenetic volcanoes of the Neogene-Quaternary Cappadocian Volcanic Province (CVP) is analyzed to investigate the relationship between vent location and regional tectonic lineaments.

TL;DR: The Bayramic magmatic complex as discussed by the authors was derived from the magmas of lithospheric mantle origin, which were later contaminated, while passing through the thick continental crust, in a post-collisional tectonic tectonics setting, during the Oligocene-Early Miocene period.

TL;DR: In this paper, a numerical approach to simulate the surficial processes responsible for the erosion of a typical scoria cone is presented. But the authors focus on the degradational evolution of scoria cones in a semi-arid climate.

TL;DR: The Whakamaru group ignimbrites are widespread voluminous welded ignimrites which crop out along the eastern and western margins of the Taupo Volcanic Zone (TVZ), New Zealand as discussed by the authors.

TL;DR: In this paper, a complex thermodynamic-microphysical package has been formulated that is able to deal with the microphysical processes of condensed water vapour in a volcanic plume.

TL;DR: The Ezine region is located in the northwestern part of Anatolia where young granitic and volcanic rocks are widespread and show close spatial and temporal association as discussed by the authors, and the volcanic rocks may be divided into two main groups on the basis of their lithological properties.