scholarly journals The strength and permeability of tuffisite-bearing andesite in volcanic conduits

2012 ◽  
Vol 4 (1) ◽  
pp. 459-473 ◽  
Author(s):  
S. Kolzenburg ◽  
M. J. Heap ◽  
Y. Lavallée ◽  
J. K. Russell ◽  
P. G. Meredith ◽  
...  
Keyword(s):  
Lower Boundary ◽  
Rock Properties ◽  
Continuous Increase ◽  
Wave Velocities ◽  
Seismic Wave Velocities ◽  
Volcanic Processes ◽  
Andesitic Rock ◽  
Short Time ◽  
Fundamental Physical ◽  
Upper Boundary

Abstract. Tuffisites result from volcanically-induced subsurface fragmentation, transport and deposition, and are common in explosive volcanic environments. Their study provides direct insight to explosive volcanic processes operating within volcanic conduits. Here we report the influence of tuffisite veins on the fundamental physical properties of andesitic rocks. We find that: (1) strength is unaffected by the presence and/or orientation of tuffisites, (2) permeability doubles when tuffisites are oriented favorable (45 degrees to fluid flow), and (3) seismic wave velocities show a continuous increase with depth, independent of vein orientation. Although the influence of tuffisites on andesitic rock properties is modest, we emphasize that the material tested represents the post-eruptive state of tuffisite. Thus, these results delineate the upper boundary of strength and lower boundary of permeability and porosity. All evidence suggests that tuffisites become compacted and lithified on relatively short time scales, restoring the strength of the rock to their initial host rock values.

scholarly journals Strength and permeability recovery of tuffisite-bearing andesite

Solid Earth ◽  
2012 ◽  
Vol 3 (2) ◽  
pp. 191-198 ◽  
Author(s):  
S. Kolzenburg ◽  
M. J. Heap ◽  
Y. Lavallée ◽  
J. K. Russell ◽  
P. G. Meredith ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fluid Flow ◽  
Physical Properties ◽  
Ultrasonic Wave ◽  
Flow Direction ◽  
Rock Properties ◽  
Continuous Increase ◽  
Wave Velocities ◽  
Andesitic Rock ◽  
Host Rocks

Abstract. Tuffisites, the products of subsurface fragmentation, transport and deposition, are common in explosive volcanic environments. Their study provides direct insight to the mechanical processes operating within volcanic conduits. Here we document the influence of the presence of coherent tuffisite veins on the physical properties of andesitic rocks. We find that (1) compressive strength is unaffected by the presence and/or orientation of tuffisites, (2) permeability doubles when tuffisites are oriented favorably (at 45° to the fluid flow direction), and (3) ultrasonic wave velocities show a continuous increase with depth, independent of vein presence and orientation. Although the influence of tuffisites on andesitic rock properties determined here is modest, we emphasize that the material tested represents the post-eruptive state of tuffisite. Thus, these results likely delineate the upper and lower boundaries of strength vs. permeability and porosity, respectively. Our evidence suggests that, via compaction and lithification, tuffisites may restore the strength of the volcanic host-rocks to that of their pre-tuffisite values.

A Consistent Time-Split Numerical Scheme Applied to the Nonhydrostatic Compressible Equations*

2007 ◽  
Vol 135 (1) ◽  
pp. 20-36 ◽  
Author(s):  
Almut Gassmann ◽  
Hans-Joachim Herzog
Keyword(s):  
Boundary Condition ◽  
Lower Boundary ◽  
Fast Mode ◽  
Time Step ◽  
Lower Boundary Condition ◽  
The One ◽  
Consistent Treatment ◽  
Short Time ◽  
The Given ◽  
Upper Boundary

Abstract The primary interest of the paper is to apply a two-time-level split explicit time scheme developed by one of the authors to the Lokal-Modell (LM) of the German Weather Service (DWD). This model belongs to the operational NWP system at DWD, which makes it particularly interesting for this study. To better understand the implementation of this time scheme in a compressible nonhydrostatic model type, and so in the LM, a linear analysis is presented demonstrating how the equations are to be split up into fast- and slow-mode parts. For the fast-mode part, this analysis demonstrates how the connected short time-step scheme is necessary for a consistent treatment of gravity modes on the one side and a sufficient damping of acoustic modes on the other side. An extended linear stability analysis for the new splitting scheme follows then to establish its application in a full model. An advantage of the given time scheme is that any forward-in-time and stable advection scheme can be linked with the reformulated fast-mode equation part. A Runge–Kutta third-order-in-time and second-order-in-space scheme (RK3/2) has been applied to the horizontal advection, and the vertical advection terms are treated implicitly. A new consistent lower boundary condition and a radiative upper boundary condition are taken into account. Steady airflow simulations over an isolated mountain (Schär test) and the successful incorporation of the Klemp–Durran–Bougeault radiative upper boundary condition in the vertically implicit fast-mode scheme confirm the given approach as necessary and effective for the application of the time scheme.

scholarly journals ON DIVERSITY OF CONFIGURATIONS GENERATED BY EXCITABLE CELLULAR AUTOMATA WITH DYNAMICAL EXCITATION INTERVALS

2012 ◽  
Vol 23 (12) ◽  
pp. 1250085 ◽  
Author(s):  
ANDREW ADAMATZKY
Keyword(s):  
Cellular Automata ◽  
Lower Boundary ◽  
Morphological Diversity ◽  
Excitable Media ◽  
Stationary Waves ◽  
Future Studies ◽  
Time Dynamics ◽  
Wide Range ◽  
Localized Excitations ◽  
Upper Boundary

Excitable cellular automata with dynamical excitation interval exhibit a wide range of space-time dynamics based on an interplay between propagating excitation patterns which modify excitability of the automaton cells. Such interactions leads to formation of standing domains of excitation, stationary waves and localized excitations. We analyzed morphological and generative diversities of the functions studied and characterized the functions with highest values of the diversities. Amongst other intriguing discoveries we found that upper boundary of excitation interval more significantly affects morphological diversity of configurations generated than lower boundary of the interval does and there is no match between functions which produce configurations of excitation with highest morphological diversity and configurations of interval boundaries with highest morphological diversity. Potential directions of future studies of excitable media with dynamically changing excitability may focus on relations of the automaton model with living excitable media, e.g. neural tissue and muscles, novel materials with memristive properties and networks of conductive polymers.

Effect of Fluids on the Elastic Properties of 3D-Printed Anisotropic Rock Models

2021 ◽  
Vol 62 (5) ◽  
pp. 537-552
Author(s):  
Suresh Dande ◽  
◽  
Robert R. Stewart ◽  
Nikolay Dyaur ◽  
◽  
...  
Keyword(s):  
Wave Propagation ◽  
Elastic Properties ◽  
P Wave ◽  
Engine Oil ◽  
Rock Properties ◽  
Anisotropic Rock ◽  
Wave Velocities ◽  
Inclusion Model ◽  
3D Printed ◽  
Primary Porosity

Laboratory physical models play an important role in understanding rock properties and wave propagation, both theoretically and at the field scale. In some cases, 3D-printing technology can be adopted to construct complex rock models faster, more inexpensively, and with more specific features than previous model-building techniques. In this study, we use 3D-printed rock models to assist in understanding the effects of various fluids (air, water, engine oil, crude oil, and glycerol) on the models’ elastic properties. We first used a 3D-printed, 1-in. cube-shaped layered model. This model was created with a 6% primary porosity and a bulk density of 0.98 g/cc with VTI anisotropy. We next employed a similar cube but with horizontal inclusions embedded in the layered background, which contributed to its total 24% porosity (including primary porosity). For air to liquid saturation, P-velocities increased for all liquids in both models, with the highest increase being with glycerol (57%) and an approximately 45% increase for other fluids in the inclusion model. For the inclusion model (dry and saturated), we observed a greater difference between two orthogonally polarized S-wave velocities (Vs1 and Vs2) than between two P-wave velocities (VP0 and VP90). We attribute this to the S2-wave (polarized normal to both the layering and the plane of horizontal inclusions), which appears more sensitive to horizontal inclusions than the P-wave. For the inclusion model, Thomsen’s P-wave anisotropic parameter (ɛ) decreased from 26% for the air case to 4% for the water-saturated cube and to 1% for glycerol saturation. The small difference between the bulk modulus of the frame and the pore fluid significantly reduces the velocity anisotropy of the medium, making it almost isotropic. We compared our experimental results with theory and found that predictions using Schoenberg’s linear slip theory combined with Gassmann’s anisotropic equation were closer to actual measurements than Hudson’s isotropic calculations. This work provides insights into the usefulness of 3D-printed models to understand elastic rock properties and wave propagation under various fluid saturations.

scholarly journals A 3-D RBF-FD solver for modeling the atmospheric global electric circuit with topography (GEC-RBFFD v1.0)

2015 ◽  
Vol 8 (10) ◽  
pp. 3007-3020 ◽  
Author(s):  
V. Bayona ◽  
N. Flyer ◽  
G. M. Lucas ◽  
A. J. G. Baumgaertner
Keyword(s):  
Numerical Model ◽  
Differential Operators ◽  
Lower Boundary ◽  
Elliptic Partial Differential Equation ◽  
Electric Circuit ◽  
Global Electric Circuit ◽  
Mesh Free ◽  
Conductivity Profile ◽  
The Right ◽  
Upper Boundary

Abstract. A numerical model based on radial basis function-generated finite differences (RBF-FD) is developed for simulating the global electric circuit (GEC) within the Earth's atmosphere, represented by a 3-D variable coefficient linear elliptic partial differential equation (PDE) in a spherically shaped volume with the lower boundary being the Earth's topography and the upper boundary a sphere at 60 km. To our knowledge, this is (1) the first numerical model of the GEC to combine the Earth's topography with directly approximating the differential operators in 3-D space and, related to this, (2) the first RBF-FD method to use irregular 3-D stencils for discretization to handle the topography. It benefits from the mesh-free nature of RBF-FD, which is especially suitable for modeling high-dimensional problems with irregular boundaries. The RBF-FD elliptic solver proposed here makes no limiting assumptions on the spatial variability of the coefficients in the PDE (i.e., the conductivity profile), the right hand side forcing term of the PDE (i.e., distribution of current sources) or the geometry of the lower boundary.

scholarly journals Theoretical Gravity Anomalies of Glaciers Having Parabolic Cross-Sections

1964 ◽  
Vol 5 (38) ◽  
pp. 255-257 ◽  
Author(s):  
Charles E. Corbató
Keyword(s):  
Cross Sections ◽  
Lower Boundary ◽  
Gravity Anomalies ◽  
Vertical Axis ◽  
Two Dimensional ◽  
Axis Of Symmetry ◽  
Upper Boundary

AbstractEquations and a graph are presented for calculating gravity anomalies on a two-dimensional glacier model having a horizontal upper boundary and a lower boundary which is a parabola with a vertical axis of symmetry.

Sign in / Sign up

Export Citation Format

Share Document