Ejecta velocities, magma chamber pressure and kinetic energy associated with the 1968 eruption of arenal volcano

1971 ◽  
Vol 35 (2) ◽  
pp. 383-401 ◽  
Author(s):  
R. F. Fudali ◽  
W. G. Melson
Keyword(s):  
Kinetic Energy ◽  
Magma Chamber ◽  
Chamber Pressure ◽  
Arenal Volcano

A critical magma chamber size for volcanic eruptions

Geology ◽  
2020 ◽  
Vol 48 (5) ◽  
pp. 431-435 ◽  
Author(s):  
Meredith Townsend ◽  
Christian Huber
Keyword(s):  
Magma Chamber ◽  
Scaling Law ◽  
Volcanic Eruptions ◽  
Elastic Response ◽  
Chamber Pressure ◽  
Pressure Drops ◽  
Chamber Volume ◽  
Intermediate Chamber ◽  
History Of ◽  
Chamber Size

Abstract We present a model for a coupled magma chamber–dike system to investigate the conditions required to initiate volcanic eruptions and to determine what controls the size of eruptions. The model combines the mechanics of dike propagation with internal chamber dynamics including crystallization, volatile exsolution, and the elastic response of the magma and surrounding crust to pressure changes within the chamber. We find three regimes for dike growth and eruptions: (1) below a critical magma chamber size, eruptions are suppressed because chamber pressure drops to lithostatic before a dike reaches the surface; (2) at an intermediate chamber size, the erupted volume is less than the dike volume (“dike-limited” eruption regime); and (3) above a certain chamber size, dikes can easily reach the surface and the erupted volume follows a classic scaling law, which depends on the attributes of the magma chamber (“chamber-limited” eruption regime). The critical chamber volume for an eruption ranges from ∼0.01 km3 to 10 km3 depending on the water content in the magma, depth of the chamber, and initial overpressure. This implies that the first eruptions at a volcano likely are preceded by a protracted history of magma chamber growth at depth, and that the crust above the magma chamber may have trapped several intrusions or “failed eruptions.” Model results can be combined with field observations of erupted volume, pressure, and crystal and volatile content to provide tighter constraints on parameters such as the eruptible chamber size.

scholarly journals The dynamics of dual-magma-chamber system during volcanic eruptions inferred from physical modeling

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Tomofumi Kozono
Keyword(s):  
Analytical Solution ◽  
Magma Chamber ◽  
Volcanic Eruptions ◽  
Chamber Pressure ◽  
Deformation Pattern ◽  
Chamber System ◽  
Plumbing System ◽  
Magma Chambers ◽  
Magma Flow ◽  
Magma Plumbing System

AbstractA magma plumbing system with dual magma chambers beneath active volcanoes is commonly observed through petrological and geophysical measurements. This paper developed a physical model for the dynamics of a dual-magma-chamber system during volcanic eruptions. The model consists of the plumbing system where two elastically deformable magma chambers are connected in series with non-deformable conduits. Based on this model, we obtained an analytical solution that describes temporal changes in pressures at the two chambers accompanied by the eruption. The analytical solution showed that the feature of the chamber pressure changes is mainly controlled by two non-dimensional numbers $$C'$$ C ′ and $$\Omega '$$ Ω ′ . Here, $$C'$$ C ′ is the ratio of the parameter controlling the magnitude of pressure change in the shallower chamber to that in the deeper chamber, and $$\Omega '$$ Ω ′ is the ratio of conduit’s conductivity (inverse of resistivity to magma flow) between the shallower chamber and the surface to that between the chambers. For smaller $$C'$$ C ′ and $$\Omega '$$ Ω ′ , the shallower chamber’s pressure is kept constant during the decrease in the pressure at the deeper chamber in the initial phase of the eruption. This corresponds to a deformation pattern commonly observed in some eruptions, in which the deflation of the deeper chamber was predominant. The estimation of $$C'$$ C ′ and $$\Omega '$$ Ω ′ based on the parameters related to magma properties and geometries of the chambers and the conduits revealed that the smaller $$C'$$ C ′ and $$\Omega '$$ Ω ′ conditions are satisfied under realistic magmatic and geological parameters. This indicates that the magma dynamics in the dual-chamber system generally cause the dominance of the deeper chamber’s deflation.

Residual Gas Reaction in the Electron Microscope: II The Design of a Gas-Control Chamber for Quantitative Observations

1969 ◽  
Vol 27 ◽  
pp. 82-83
Author(s):  
Chester J. Calbick ◽  
Richard E. Hartman
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Local Environment ◽  
Chamber Pressure ◽  
Objective Lens ◽  
Ion Pump ◽  
Quantitative Studies ◽  
Precise Knowledge ◽  
Differential Pumping ◽  
And Control

Quantitative studies of the phenomenon associated with reactions induced by the electron beam between specimens and gases present in the electron microscope require precise knowledge and control of the local environment experienced by the portion of the specimen in the electron beam. Because of outgassing phenomena, the environment at the irradiated portion of the specimen is very different from that in any place where gas pressures and compositions can be measured. We have found that differential pumping of the specimen chamber by a 4" Orb-Ion pump, following roughing by a zeolite sorption pump, can produce a specimen-chamber pressure 100- to 1000-fold less than that in the region below the objective lens.

Studies of the scanning ion beam sputter-cleaned MgO crystal surface by scanning reflection electron microscopy

1987 ◽  
Vol 45 ◽  
pp. 144-145
Author(s):  
H.-J. Ou ◽  
J. M. Cowley ◽  
A. A. Higgs
Keyword(s):  
Crystal Surface ◽  
Ion Beam ◽  
Carbon Film ◽  
Surface Region ◽  
Bulk Sample ◽  
Chamber Pressure ◽  
Specimen Preparation ◽  
Detailed Surface ◽  
Gate Control ◽  
Reflection Electron Microscopy

A scanning ion gun system has been installed on the specimen preparation chamber (pressure ∼5xl0-8 torr) of the VG-HB5 STEM microscope. By using the specimen current imaging technique, it is possible to use an ion beam to sputter-clean the preferred surface region on a bulk sample. As shown in figure 1, the X-Y raster-gate control of the scanning unit for the Krato Mini-Beam I is used to minimize the beam raster area down to a 800μm x800μm square region. With beam energy of 2.5KeV, the MgO cleavage surface has been ion sputter-cleaned for less than 1 minute. The carbon film or other contaminant, introduced during the cleavage process in air, is mostly removed from the MgO crystal surfaces.The immediate SREM inspection of this as-cleaned MgO surface, within the adjacent STEM microscope, has revealed the detailed surface structures of atomic steps, which were difficult to observe on the as-cleaved MgO surfaces in the previous studies.

Electron behavior in the gaseous environment of the ESEM chamber

1996 ◽  
Vol 54 ◽  
pp. 838-839 ◽  
Author(s):  
S.A. Wight
Keyword(s):  
Secondary Electron ◽  
High Vacuum ◽  
Beam Current ◽  
Chamber Pressure ◽  
Environmental Scanning ◽  
Carbon Block ◽  
Faraday Cup ◽  
X Ray ◽  
Gaseous Environment ◽  
Working Distance

Measurements of electrons striking the sample in the Environmental Scanning Electron Microscope (ESEM) are needed to begin to understand the effect of the presence of the gas on analytical measurements. Accurate beam current is important to x-ray microanalysis and it is typically measured with a faraday cup. A faraday cup (Figure 1) was constructed from a carbon block embedded in non-conductive epoxy with a 45 micrometer bore platinum aperture over the hole. Currents were measured with an electrometer and recorded as instrument parameters were varied.Instrument parameters investigated included working distance, chamber pressure, condenser percentage, and accelerating voltage. The conditions studied were low vacuum with gaseous secondary electron detector (GSED) voltage on; low vacuum with GSED voltage off; and high vacuum (GSED off). The base conditions were 30 kV, 667 Pa (5 Torr) water vapor, 100,000x magnification with the beam centered inside aperture, GSED voltage at 370 VDC, condenser at 50%, and working distance at 19.5 mm. All modifications of instrument parameters were made from these conditions.

Dependence of the joint configuration on the dynamic immobility fulcrum

2019 ◽  
pp. 108-114
Author(s):  
A. D. Kozlov ◽  
Yu. P. Potekhina
Keyword(s):  
Kinetic Energy ◽  
Convex Surface ◽  
The Other ◽  
Concave Surface ◽  
Joint Configuration ◽  
Articular Surfaces

Although joints with synovial cavities and articular surfaces are very variable, they all have one common peculiarity. In most cases, one of the articular surfaces is concave, whereas the other one is convex. During the formation of a joint, the epiphysis, which has less kinetic energy during the movements in the joint, forms a convex surface, whereas large kinetic energy forms the epiphysis with a concave surface. Basing on this concept, the analysis of the structure of the joints, allows to determine forces involved into their formation, and to identify the general patterns of the formation of the skeleton.

Sign in / Sign up

Export Citation Format

Share Document