Showing papers in "Journal of Volcanology and Geothermal Research in 1993"

TL;DR: The trachytic Campanian ignimbrite, originally exposed over a 30,000-km 2 area around Naples, Italy, is the product of a highly energetic, gas-rich eruption as discussed by the authors.

TL;DR: In this article, a detailed reconstruction of the 1631 A.D. eruption of Vesuvius is presented, with preference given to the authors who eyewitnessed the volcanic phenomena.

TL;DR: In this article, a new way to study the dynamics of explosive behavior at different vents of Stromboli volcano is proposed, based on computer processing of images taken by an infrared film camera, at a rate of 4 pictures per second.

TL;DR: The Unzen Volcano was still active with a nearly constant magma-supply rate of about 3 × 106 m3/d by the beginning of November 1991 as mentioned in this paper The total volume of the lava domes is more than 23 × 106m3.

TL;DR: In this paper, the authors quantify the relevant parameters and determine stable bubble size and critical film thickness in a foam as a function of melt viscosity, surface tension, and time.

TL;DR: The main effort of the 1992 operation consisted of several attempts at stopping the lava front advance by diverting the flow out from the natural and extensively tunnelled channel through a skylight near the vent as discussed by the authors.

TL;DR: A detailed stratigraphic analysis of the Avellino plinian deposit of the Somma-Vesuvius volcano shows a complicated eruptive sequence controlled by a combination of magmatic and hydromagmatic processes as discussed by the authors.

TL;DR: In this paper, the authors investigated the origin of the Citlaltepetl lahar and found that it had an origin as a sector collapse of hydrothermally altered rock that transformed from a debris avalanche to a cohesive lahar very close to its source.

TL;DR: The volcano appears to have reached a stage of quiescence because it finally attained a shape of equilibrium in which the height of the mountain is sufficient to counterbalance the buoyancy of the magma as discussed by the authors.

TL;DR: In this article, two main types of Hawaiian pahoehoe lava, P-type (pipe vesicle-bearing) and S-type(spongy) are characterized.

TL;DR: In this paper, the authors investigated the origin of felsic lava flows in the North Shore Volcanic Group (NSVG) and concluded that all the icelandites and some rhyolites were emplaced as large, moderately to very fluid lava flows that spread widely while crystallizing tridymite, and that some large pyroclastic flows subsequently remobilized as rheoignimbrites.

TL;DR: In this article, the melt inclusions in olivine phenocrysts from basaltic tephra erupted by Etna volcano during the 1989-1990 eruptive period were investigated for major elements, Cl and S by electron microprobe, fluorine by PIGME (Particule Induced Gamma-ray Emission) and H 2 O by SIMS.

TL;DR: In this article, the authors used historical data of an individual volcano, Colima in Mexico, to classify its eruptions by size using the Volcanic Explosivity Index (VEI).

TL;DR: The detailed analysis of the craters of hydrothermal eruptions and related products present on Nisyros Island demonstrates the ephemerality of these morphological forms as mentioned in this paper. In other words, the mere recognizable existence of the Craters and associated deposits implies recency of Hydrothermal activity, and the minimum temperature required to cause the explosive phenomenon and, possibly, the depth of the reservoir (which can be evaluated on the basis of the correlation between the diameter of the crater and the depths of the explosion as proposed by Fytikas and Marinelli, 1976) are

TL;DR: In this paper, the authors reviewed contemporary accounts of the violent eruption of Vesuvius in 1631, and recorded events are correlated with resulting volcanic deposits, showing reverse grading of pumice layers.

TL;DR: In this paper, the authors examined cumulate and subeffusive nodules from the 3800 y.B. Avellino and A.D. 472 Pollena eruptions to assess the fluids attending crystallization and to place constraints on the pressure and temperature of nodule formation.

TL;DR: In this article, the authors analyzed the effect of stress-strain discontinuities on the ground deformation generated by a pressure source and found that the location of the discontinuity controls the extension of the deformed zone, and always reduces it with respect to a continuous medium.

TL;DR: In the Ultima Esperanza District of southern Chile, extensive masses of peperite were produced when rhyolite magma underwent quenching, disruption, and commingling with wet, unconsolidated sediments during intrusion at shallow levels beneath the sea floor as mentioned in this paper.

TL;DR: A 15-km diameter topographic depression, marked by inward dips of 4-8 at the cooling unit contact, is interpreted as a downsag caldera formed during emplacement of the lower cooling unit.

TL;DR: The Ottaviano eruption of the late neolithic (8000 y B.P) as discussed by the authors was characterized by variations in the eruptive intensity, and several pyroclastic flows were emplaced (F1 to F3).

TL;DR: In this article, a model of caldera formation which assumes an enlargement of the ring fracture during a first plinian and dacitic, then essentially hydrobasaltic eruption is proposed.

TL;DR: The existence of compositional zoning in Mangakino magmas, as opposed to the generally homogeneous rhyolite magmas in the eastern centres within the Taupo Volcanic Zone, could be explained by lower heat flows as mentioned in this paper.

TL;DR: In this article, the ascent of the A.D. 79 eruption of Vesuvius was studied by a steady-state, one-dimensional, and nonequilibrium two-phase flow model.

TL;DR: In this paper, the authors detected magnetic changes associated with volcanic activity of Aso volcano with a dense network of continuously recording proton-precession magnetometers during the period from June 1989 to June 1990 Magnetic date clearly indicate that changes in the magnetization within the volcano are most probably caused by temperature changes.

TL;DR: In this article, the authors show that the presence or absence of calc-silicates is mainly controlled by the PCO2 in the system, even where temperature has played an important role.

TL;DR: In this article, a conceptual hydrogeochemical model of Nisyros Island can be used to reconstruct past hydrothermal eruptions and to estimate the risk of such events happening again in the future.

TL;DR: In this article, it is suggested that the major eruption started with the generation of a pyroclastic flow, which was subsequently followed by a plinian eruption resulting in the formation of the giant cloud and the lapilli fall.

TL;DR: The Masaya Caldera Complex has a number of distinctive geochemical features: relative compositional homogeneity, low Al2O3 and high FeO contents, a tholeitic differentiation trend, and elevated, large-ion-lithophile (LIL)-element concentrations (e.g., Ba ∼ 800 ppm) on CMAS projections.