scholarly journals Comparison of elastic moduli from seismic diving-wave and ice-core microstructure analysis in Antarctic polar firn

2019 ◽  
Vol 60 (79) ◽  
pp. 220-230 ◽  
Author(s):  
Rebecca Schlegel ◽  
Anja Diez ◽  
Henning Löwe ◽  
Christoph Mayer ◽  
Astrid Lambrecht ◽  
...  
Keyword(s):  
Elastic Moduli ◽  
Seismic Velocity ◽  
Ice Core ◽  
S Wave ◽  
Uncertainty Range ◽  
Wave Refraction ◽  
Refraction Seismic ◽  
Dynamic Elastic Moduli ◽  
Static Elastic Moduli ◽  
Firn Core

ABSTRACTWe compared elastic moduli in polar firn derived from diving wave refraction seismic velocity analysis, firn-core density measurements and microstructure modelling based on firn-core data. The seismic data were obtained with a small electrodynamic vibrator source near Kohnen Station, East Antarctica. The analysis of diving waves resulted in velocity–depth profiles for different wave types (P-, SH- and SV-waves). Dynamic elastic moduli of firn were derived by combining P- and S-wave velocities and densities obtained from firn-core measurements. The structural finite-element method (FEM) was used to calculate the components of the elastic tensor from firn microstructure derived from X-ray tomography of firn-core samples at depths of 10, 42, 71 and 99 m, providing static elastic moduli. Shear and bulk moduli range from 0.39 to 2.42 GPa and 0.68 to 2.42 GPa, respectively. The elastic moduli from seismic observations and the structural FEM agree within 8.5% for the deepest achieved values at a depth of 71 m, and are within the uncertainty range. Our observations demonstrate that the elastic moduli of the firn can be consistently obtained from two independent methods which are based on dynamic (seismic) and static (tomography and FEM) observations, respectively, for deeper layers in the firn below ~10 m depth.

Investigations of andesitic volcanic debris terrains: Part 2 — Geotechnical

Geophysics ◽  
2006 ◽  
Vol 71 (1) ◽  
pp. B9-B15 ◽  
Author(s):  
Derek A. Gay ◽  
Frank D. Morgan ◽  
Yervant Vichabian ◽  
John A. Sogade ◽  
Philip Reppert ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Elastic Moduli ◽  
Seismic Velocity ◽  
Dynamic Elastic Modulus ◽  
Geotechnical Investigation ◽  
Geophysical Investigation ◽  
Geotechnical Investigations ◽  
Dynamic Elastic Moduli ◽  
Volcanic Debris ◽  
Data Correlations

Here, results of geotechnical investigations for the proposed Dominica international airport are presented. The main geotechnical investigative method is comprised of boreholes to 30 m depth with standard penetrating testing (SPT) and undisturbed Shelby tube and disturbed split-spoon soil sampling. The geotechnical investigation confirms the findings of a companion geophysical investigation, which concludes that bedrock is not likely to be encountered within the proposed depths of excavation for the airport. Geophysical and geotechnical data correlations are developed. Seismic velocity and the number N of blow counts with SPT (SPT N) appear to be well correlated by a linear model. A model relationship between SPT and seismic dynamic elastic modulus is developed using seismic velocity. SPT N is better correlated with the dynamic elastic modulus than with seismic velocity. The study shows that the seismic velocity and the derived dynamic elastic moduli can accurately predict soil strength as measured by SPT blow counts.

scholarly journals Influence of ice crystal anisotropy on seismic velocity analysis

2014 ◽  
Vol 55 (67) ◽  
pp. 97-106 ◽  
Author(s):  
Anja Diez ◽  
Olaf Eisen ◽  
Ilka Weikusat ◽  
Jan Eichler ◽  
Coen Hofstede ◽  
...  
Keyword(s):  
Seismic Velocity ◽  
Ice Core ◽  
Radar Data ◽  
P Wave ◽  
Seismic Survey ◽  
Sh Wave ◽  
Wave Analysis ◽  
S Wave ◽  
Alpine Glacier ◽  
Reflection Seismic

AbstractIn 2010 a reflection seismic survey was carried out on the Alpine glacier Colle Gnifetti. The processed and depth-converted data could be compared to a nearby ice core, drilled almost to the bed. Comparisons showed that the depth of the P-wave bed reflection was too shallow, while the depth of the SH-wave bed reflection fitted the ice-core length well. We are now able to explain the major part of these differences using the existing crystal orientations of the ice at Colle Gnifetti. We calculate anisotropic velocities for P- and SH-waves that are usually picked for stacking and compare them with zero-offset velocities needed for the depth conversion. Here we take the firn pack at Colle Gnifetti into account for P- and S-wave analysis. To incorporate the S-wave analysis we first derive a new equation for the relationship between density and S-wave velocity from diving waves. We show that anisotropic fabrics observed at Colle Gnifetti introduce a difference of only 1% between stacking and depth-conversion velocities for the SH-wave, but 7% for the P-wave. We suggest that this difference in stacking and depth-conversion velocity for the P-wave can be used to derive information about the existing anisotropy by combining our seismic data with, for example, radar data.

scholarly journals Analysis of Near Surface Seismic Refraction for Geotechnical Parameters in Opolo, Yenagoa of Bayelsa State

2019 ◽  
pp. 1-12
Author(s):  
Francis Omonefe ◽  
Eteh Desmond ◽  
Oborie Ebiegberi ◽  
Oboshenure Kingsley Karo
Keyword(s):  
Seismic Velocity ◽  
Seismic Refraction ◽  
Constant Density ◽  
S Wave ◽  
Seismic Profiles ◽  
Near Surface ◽  
Underdeveloped Area ◽  
Refraction Seismic ◽  
Subsurface Soil ◽  
A Site

Three surface refraction seismic profiles were conducted in a site targeted for huge construction in an underdeveloped area in Opolo, Yenagoa city to portray some of the subsurface soil engineering characteristics for the purposes of construction. The Generalized Reciprocal Method (GRM) was used to interpret the acquired P and S-wave. Various shallow rock engineering parameters such as Oedometric modulus, Concentration Index, Material Index, Lame’s constant, Density Gradient, Stress Ratio, Shear modulus, Bearing capacity, and N-value were calculated in other to assess the strength of the subsurface  from a geophysical and engineering perspective. The values from the seismic velocity and strength parameters indicates that the bedrock layer (layer 3) of the area studied is characterized by more competent rock quality than layer 1 and 2. Hence, the Opolo site is suggested for construction activities with percussive measures.

A comparative study of the anisotropic dynamic and static elastic moduli of unconventional reservoir shales: Implication for geomechanical investigations

Geophysics ◽  
2016 ◽  
Vol 81 (3) ◽  
pp. D245-D261 ◽  
Author(s):  
Jaime Meléndez-Martínez ◽  
Douglas R. Schmitt
Keyword(s):  
Bedding Plane ◽  
Horizontal Stress ◽  
Pressure Sensitivity ◽  
S Wave ◽  
Fracture Pressure ◽  
Highly Nonlinear ◽  
Rock Anisotropy ◽  
Minimum Stress ◽  
Sonic Logging ◽  
Static Elastic Moduli

We obtained the complete set of dynamic elastic stiffnesses for a suite of “shales” representative of unconventional reservoirs from simultaneously measured P- and S-wave speeds on single prisms specially machined from cores. Static linear compressibilities were concurrently obtained using strain gauges attached to the prism. Regardless of being from static or dynamic measurements, the pressure sensitivity varies strongly with the direction of measurement. Furthermore, the static and dynamic linear compressibilities measured parallel to the bedding are nearly the same whereas those perpendicular to the bedding can differ by as much as 100%. Compliant cracklike porosity, seen in scanning electron microscope images, controls the elastic properties measured perpendicular to the rock’s bedding plane and results in highly nonlinear pressure sensitivity. In contrast, those properties measured parallel to the bedding are nearly insensitive to stress. This anisotropy to the pressure dependency of the strains and moduli further complicates the study of the overall anisotropy of such rocks. This horizontal stress insensitivity has implications for the use of advanced sonic logging techniques for stress direction indication. Finally, we tested the validity of the practice of estimating the fracture pressure gradient (i.e., horizontal stress) using our observed elastic engineering moduli and found that ignoring anisotropy would lead to underestimates of the minimum stress by as much as 90%. Although one could ostensibly obtain better values or the minimum stress if the rock anisotropy is included, we would hope that these results will instead discourage this method of estimating horizontal stress in favor of more reliable techniques.

scholarly journals Temperature dependence of dynamic elastic moduli of wrought aluminum alloys

1972 ◽  
Vol 22 (12) ◽  
pp. 710-715 ◽  
Author(s):  
Hiroshi NEWKO ◽  
Shigeo ZAIMA ◽  
Yoitiro TAKEUTI ◽  
Kazuo TAMARU
Keyword(s):  
Aluminum Alloys ◽  
Temperature Dependence ◽  
Elastic Moduli ◽  
Dynamic Elastic Moduli ◽  
Wrought Aluminum Alloys ◽  
Wrought Aluminum

Static and dynamic elastic moduli of rock in a complex axisymmetric stressed state

1984 ◽  
Vol 20 (5) ◽  
pp. 343-350 ◽  
Author(s):  
A. N. Stavrogin ◽  
G. G. Zaretskii-Feoktistov ◽  
G. N. Tanov
Keyword(s):  
Stressed State ◽  
Elastic Moduli ◽  
Dynamic Elastic Moduli

scholarly journals Effects of the width and lay-up of sugi cross-laminated timber (CLT) on its dynamic and static elastic moduli, and tensile strength

2015 ◽  
Vol 62 (1) ◽  
pp. 101-108 ◽  
Author(s):  
Hirofumi Ido ◽  
Hirofumi Nagao ◽  
Masaki Harada ◽  
Hideo Kato ◽  
Junko Ogiso ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Elastic Moduli ◽  
Cross Laminated Timber ◽  
Static Elastic Moduli

The relation between seismic P‐ and S‐wave velocity dispersion in saturated rocks

Geophysics ◽  
1994 ◽  
Vol 59 (1) ◽  
pp. 87-92 ◽  
Author(s):  
Gary Mavko ◽  
Diane Jizba
Keyword(s):  
Wave Velocity ◽  
Large Scale ◽  
Velocity Dispersion ◽  
Seismic Velocity ◽  
Ultrasonic Velocities ◽  
S Wave ◽  
Local Flow ◽  
Wave Velocities ◽  
Shear Compliance

Seismic velocity dispersionin fluid-saturated rocks appears to be dominated by tow mecahnisms: the large scale mechanism modeled by Biot, and the local flow or squirt mecahnism. The tow mechanisms can be distuinguished by the ratio of P-to S-wave dispersions, or more conbeniently, by the ratio of dynamic bulk to shear compliance dispersions derived from the wave velocities. Our formulation suggests that when local flow denominates, the dispersion of the shear compliance will be approximately 4/15 the dispersion of the compressibility. When the Biot mechanism dominates, the constant of proportionality is much smaller. Our examination of ultrasonic velocities from 40 sandstones and granites shows that most, but not all, of the samples were dominated by local flow dispersion, particularly at effective pressures below 40 MPa.

scholarly journals Landslide characterization using P- and S-wave seismic refraction tomography — The importance of elastic moduli

2016 ◽  
Vol 134 ◽  
pp. 64-76 ◽  
Author(s):  
S. Uhlemann ◽  
S. Hagedorn ◽  
B. Dashwood ◽  
H. Maurer ◽  
D. Gunn ◽  
...  
Keyword(s):  
Elastic Moduli ◽  
Seismic Refraction ◽  
S Wave ◽  
Refraction Tomography

scholarly journals Antarctic Upper Mantle Rheology

2021 ◽  
pp. M56-2020-19
Author(s):  
E. R. Ivins ◽  
W. van der Wal ◽  
D. A. Wiens ◽  
A. J. Lloyd ◽  
L. Caron
Keyword(s):  
Wave Velocity ◽  
Upper Mantle ◽  
Effective Viscosity ◽  
Seismic Velocity ◽  
Imaging Techniques ◽  
Three Dimensional ◽  
Velocity Model ◽  
Mantle Flow ◽  
S Wave ◽  
Velocity Changes

AbstractThe Antarctic mantle and lithosphere are known to have large lateral contrasts in seismic velocity and tectonic history. These contrasts suggest differences in the response time scale of mantle flow across the continent, similar to those documented between the northeastern and southwestern upper mantle of North America. Glacial isostatic adjustment and geodynamical modeling rely on independent estimates of lateral variability in effective viscosity. Recent improvements in imaging techniques and the distribution of seismic stations now allow resolution of both lateral and vertical variability of seismic velocity, making detailed inferences about lateral viscosity variations possible. Geodetic and paleo sea-level investigations of Antarctica provide quantitative ways of independently assessing the three-dimensional mantle viscosity structure. While observational and causal connections between inferred lateral viscosity variability and seismic velocity changes are qualitatively reconciled, significant improvements in the quantitative relations between effective viscosity anomalies and those imaged by P- and S-wave tomography have remained elusive. Here we describe several methods for estimating effective viscosity from S-wave velocity. We then present and compare maps of the viscosity variability beneath Antarctica based on the recent S-wave velocity model ANT-20 using three different approaches.

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