Physical properties of deep crustal reflectors in southern California from multioffset amplitude analysis

Geophysics ◽  
1990 ◽  
Vol 55 (6) ◽  
pp. 670-681 ◽  
Author(s):  
John N. Louie
Keyword(s):  
Physical Properties ◽  
Poisson’S Ratio ◽  
Mojave Desert ◽  
Poisson's Ratio ◽  
Amplitude Analysis ◽  
Deep Crust ◽  
Amplitude Versus Offset ◽  
The Individual ◽  
Spherical Divergence ◽  
Amplitude Versus

Analysis of reflection waveforms before stack can constrain the physical properties of reflectors in the deep crust. To simplify this analysis, recorded amplitudes are assumed to be reflections from weak elastic heterogeneities. With these assumptions, trends in reflection amplitudes with offset may indicate whether the signs of a reflector’s density and rigidity contrast agree with or oppose the sign of its Lamé’s parameter contrast. The slope of the trend indicates the degree of Poisson’s ratio contrast. No attempt is made to invert for the individual modulus or density contrasts. By examining only gross amplitude‐versus‐offset (AVO) trends, deep reflections constrain some crustal properties. Two seismic reflection surveys in the Mojave Desert recorded deep reflections that show amplitude changes with offset. Both the 1985 Calcrust Ward Valley survey in the eastern Mojave and the 87 km COCORP Mojave line 3 in the western Mojave incorporate long offsets of 10 km or more. Prestack traces are equalized using a quantile technique assuming a constant noise level at large time, then corrected for spherical divergence. Gross AVO trends that are summarized for each survey in amplitude trend stacks suggest that the strongest reflectors in the middle and deep crust represent Poisson’s ratio contrasts of at least 10 percent. In the eastern Mojave, a transition to a basal‐crustal zone, at ∼23 km depth, may include an increase in Poisson’s ratio with depth. Poisson’s ratio may also increase at the Moho.

scholarly journals Thin-layer effects in glaciological seismic amplitude-versus-angle (AVA) analysis: implications for characterising a subglacial till unit, Russell Glacier, West Greenland

2012 ◽  
Vol 6 (1) ◽  
pp. 759-792 ◽  
Author(s):  
A. D. Booth ◽  
R. A. Clark ◽  
B. Kulessa ◽  
T. Murray ◽  
A. Hubbard
Keyword(s):  
Thin Layer ◽  
Physical Properties ◽  
Acoustic Impedance ◽  
Poisson’S Ratio ◽  
Greenland Ice Sheet ◽  
Poisson's Ratio ◽  
High Porosity ◽  
West Greenland ◽  
Seismic Amplitude ◽  
Amplitude Versus

Abstract. Seismic amplitude-versus-angle (AVA) methods are a powerful means of interpreting the physical properties of subglacial material, although interpreting an AVA response is complicated in the case of a thinly-layered substrate. A layer thinner than one-quarter of the seismic wavelength is considered seismically "thin", and reflections from its bounding interfaces are perceived as a single event. Since a lodged (non-deforming) subglacial till can capped by a thin (metre-scale) cap of dilatant (deforming) till, serious misinterpretations can result if thin layer considerations are not honoured. AVA responses for layered subglacial tills are simulated: we model dilatant layers of thickness 0.1–3.0 m (up to a quarter-wavelength of our synthetic seismic pulse) overlying a lodged half-space, assigning typical acoustic impedance and Poisson's ratios to each. If thin layer effects are neglected, the AVA response to ultra-thin (<1.0 m) dilatant layers yields incompatible physical properties (acoustic impedance and Poisson's ratio indicating, respectively, a low- and high-porosity unit). We show an interpretative strategy that identifies thin layer effects and accurately quantifies the modelled acoustic impedance of lodged till from the composite AVA response. We apply this method to example seismic AVA data from the Russell Glacier outlet of the West Greenland Ice Sheet, in which characteristics of thin layer responses are evident. We interpret a stratified subglacial deposit, with upper and lower layers of high-porosity (<1.0 m thick, Poisson's ratio >0.492 ± 0.015) and low-porosity (acoustic impedance of 4.20–4.39 × 106 kg m−2 s−1) material, respectively assumed to represent dilatant and lodged tills. Thin layer considerations are strongly advised wherever seismic AVA analyses are used to quantify subglacial material properties.

The Effect of Design Changes on Sound Transmission through a Building

1996 ◽  
Vol 3 (3) ◽  
pp. 145-185
Author(s):  
Robert J.M. Craik
Keyword(s):  
Young’S Modulus ◽  
Poisson’S Ratio ◽  
Young's Modulus ◽  
Sound Transmission ◽  
Poisson's Ratio ◽  
Analysis Model ◽  
Room Size ◽  
Design Changes ◽  
Small Change ◽  
The Individual

A statistical energy analysis model of a building was used to assess the effect of design changes on sound transmission. Systematic changes were made to the material properties (density, Young's modulus, Poisson's ratio and internal loss factor) and to the dimensions (thickness and room size). These changes resulted in a redistribution of the energy throughout the building causing the noise level to go up in some rooms and to go down in others. For each case examined it was found that the effect of several changes could be estimated from the sum of the individual changes. Thus a change of 20% in the density resulted in approximately double the change in DnTw that was obtained from a 10% change in density. The same additive effect was also found to apply if more than one variable was changed at the same time. Thus the change in DnTw resulting from a small change in Young's modulus for the floors and a small change in the density of the walls can be estimated from the sum of the two individual effects. Changes to the thickness and density of the walls and floors have the greatest effect on sound transmission whilst changes to Young's modulus and Poisson's ratio have a much smaller effect. Damping can also have a significant effect on transmission particularly far from the source.

Electro-mechanical anisotropy of phosphorene

Nanoscale ◽  
2015 ◽  
Vol 7 (21) ◽  
pp. 9746-9751 ◽  
Author(s):  
Luqing Wang ◽  
Alex Kutana ◽  
Xiaolong Zou ◽  
Boris I. Yakobson
Keyword(s):  
Physical Properties ◽  
Band Gap ◽  
Young’S Modulus ◽  
Poisson’S Ratio ◽  
External Stress ◽  
Mechanical Anisotropy ◽  
Poisson's Ratio ◽  
Inherent Anisotropy ◽  
Basic Properties ◽  
Effective Carrier

The external stress enhances the inherent anisotropy of phosphorene, affecting various basic physical properties including Young's modulus, Poisson's ratio, band gap, and effective carrier masses. We compute basic properties of uniaxially-stressed phosphorene and present all final results in compact analytical forms.

Exploration application of seismic amplitude analysis in the Krishna-Godavari Basin, east coast of India

2014 ◽  
Vol 2 (4) ◽  
pp. SP5-SP20 ◽  
Author(s):  
Ram Janma Singh
Keyword(s):  
Amplitude Analysis ◽  
Seismic Amplitude ◽  
High Impedance ◽  
Data Phase ◽  
Amplitude Versus Offset ◽  
Bright Spots ◽  
Strong Amplitude ◽  
Very High ◽  
Amplitude Versus ◽  
Godavari Basin

Seismic amplitude anomalies are attractive exploration targets in the Krishna-Godavari Basin offshore India. These bright spots mostly have very high amplitudes, so confident interpretations have been possible. We distinguished between hydrocarbon-bearing sands, water-bearing sands, and high-impedance nonreservoir bodies. Also, we mapped channel architecture and accurately predicted reservoir thickness. Strong amplitude anomalies, prospective seismic character based on an understanding of data phase and polarity, flat spots, and amplitude versus offset have all provided valuable evidence.

A novel SiO monolayer with a negative Poisson's ratio and Dirac semimetal properties

2020 ◽  
Vol 22 (35) ◽  
pp. 20107-20113
Author(s):  
Hui Du ◽  
Guoling Li ◽  
Jiao Chen ◽  
Zhenlong Lv ◽  
Yuanzheng Chen ◽  
...  
Keyword(s):  
Physical Properties ◽  
Poisson’S Ratio ◽  
2D Materials ◽  
Poisson's Ratio ◽  
Negative Poisson’S Ratio ◽  
Two Dimensional ◽  
2D Material ◽  
Dirac Semimetal ◽  
Negative Poisson's Ratio

Although a number of interesting physical properties such as a negative Poisson's ratio (NPR) and Dirac semimetal (DS) properties have been recently predicted in two-dimensional (2D) materials, the realization of a 2D material that exhibit both of these DS and NPR features has rarely been reported.

Ray‐geometrical analysis of dip moveout amplitude distribution

Geophysics ◽  
1989 ◽  
Vol 54 (10) ◽  
pp. 1333-1335 ◽  
Author(s):  
Valery Sorin ◽  
Shuki Ronen
Keyword(s):  
Amplitude Distribution ◽  
Geometrical Optics ◽  
Ray Theory ◽  
Geometrical Analysis ◽  
Amplitude Analysis ◽  
Process Stage ◽  
Amplitude Correction ◽  
Amplitude Versus Offset ◽  
Amplitude Versus

Amplitude analysis (such as for amplitude‐versus‐offset effects) requires a true‐amplitude correction at each process stage, including the dip moveout (DMO) process. The well known DMO operator is the “smile” smear, derived by Deregowski and Rocca (1981). In this note we continue their geometrical‐optics approach to obtain the amplitude on the operator they derived. The proposed solution is based on ray theory.

DETERMINATION OF THE PHYSICAL PROPERTIES OF COMPLEXLY CONSTRUCTED MEDIA USING NEAR-SURFACE CROSSWELL METHOD

2019 ◽  
pp. 13-20 ◽  
Author(s):  
H. Guliyev ◽  
Kh. Aghayev ◽  
F. Mehraliyev ◽  
E. Ahmadova
Keyword(s):  
Physical Properties ◽  
Poisson’S Ratio ◽  
Seismic Anisotropy ◽  
Water Saturation ◽  
Shear Waves ◽  
Practical Importance ◽  
Poisson's Ratio ◽  
High Porosity ◽  
Reservoir Pressure ◽  
Near Surface

In case when the upper part of the medium has complex geological structure and geodynamic processes occur in it, the necessity of these data increases in projecting of the object under construction. Purpose. Studying of acoustic, elastic and anisotropic properties of the upper part of section of complicatedly constructed geological media. Methodology. Seismic observations are conducted in shallow wells in the areas of construction objects located in various seismogeological conditions by NSCW (Near-Surface Cross Well testing) method. Field seismic records are processed. Kinematic and dynamic parameters of pressure and differently polarized shear waves are determined. Thin-layered one-dimensional models of physical properties of the medium are created and interpreted on the basis of nonlinear theory of elastodynamics. Results. It is determined that the medium with high porous, water saturated rocks and anomalous high reservoir pressure has anomalous low value of velocities and gradient of their increase with depth. When this medium was re-examined after deep piles were built there, the overestimated seismic velocities are obtained, which is explained by a decrease in the section of anomalously high reservoir pressure and, accordingly, the porosity of the rocks after piles were built. When the hollowness is increased in unsaturated pebble rocks, the negative value of Poisson's ratio is obtained on the standard method. Seismic anisotropy related with the direction of the grains packing of the rocks is revealed on velocities of shear waves. The change of property of rocks on depth is manifested clearer on frequencies of waves than on their amplitudes. Scientific novelty. The elasticity moduli of the 3rd order are determined which are more sensible to variability of nonlinear elastic properties of rocks of the medium than the moduli of the 2nd order. The values of Poisson's ratio are recalculated for one and the same rocks located in different conditions of rock pressure on the basis of nonclassical theory of deformation. Practical importance. The obtained results can be applied to study the media characterized by complex seismogeological hydrodynamic conditions with clay-sandy rocks of high porosity and water saturation.

Theory of CBM AVO: I. Characteristics of anomaly and why it is so

Geophysics ◽  
2014 ◽  
Vol 79 (2) ◽  
pp. D55-D65 ◽  
Author(s):  
Xin-Ping Chen ◽  
Quanming Huo ◽  
Jiandong Lin ◽  
Yang Wang ◽  
Fenjin Sun ◽  
...  
Keyword(s):  
Coalbed Methane ◽  
Methane Content ◽  
Poisson's Ratio ◽  
Elastic Parameters ◽  
Zoeppritz Equations ◽  
Amplitude Versus Offset ◽  
Study Characteristics ◽  
Amplitude Versus ◽  
Class Iv ◽  
Sweet Spots

Based on the inverse correlations between methane content and elastic parameters of coalbed methane (CBM) reservoirs and on geomodulus approximation of Zoeppritz equations, we study characteristics of CBM amplitude versus offset (AVO) anomaly. Our research first suggests that CBM AVO cannot, and needs not, cling to Poisson’s Ratio as AVO for conventional gas (C-gas) does and that various approximations of Zoeppritz equations for C-gas AVO can be applied to CBM AVO though the elastic contrasts at boundaries of CBM reservoirs cannot be said to be small compared to unity. We then show that the sweet spots within a brine-saturated high- and/or medium-rank CBM reservoir can have only Class IV AVO anomaly. The reason is that all of the three elastic reflectivities, i.e., [Formula: see text] reflectivity, [Formula: see text] reflectivity, and [Formula: see text] reflectivity, at one and the same boundary of a CBM reservoir, are always of the same sign and that [Formula: see text] reflectivity or density reflectivity or both are significant in comparison with [Formula: see text] reflectivity. Finally, we propose that density reflectivity be an indicator of methane content of a CBM reservoir whereas [Formula: see text] reflectivity should be an indicator of permeability.

scholarly journals Thin-layer effects in glaciological seismic amplitude-versus-angle (AVA) analysis: implications for characterising a subglacial till unit, Russell Glacier, West Greenland

2012 ◽  
Vol 6 (4) ◽  
pp. 909-922 ◽  
Author(s):  
A. D. Booth ◽  
R. A. Clark ◽  
B. Kulessa ◽  
T. Murray ◽  
J. Carter ◽  
...  
Keyword(s):  
Thin Layer ◽  
Seismic Data ◽  
Acoustic Impedance ◽  
Poisson’S Ratio ◽  
Water Saturation ◽  
Seismic Analysis ◽  
Poisson's Ratio ◽  
West Greenland ◽  
Seismic Amplitude ◽  
Amplitude Versus

Abstract. Seismic amplitude-versus-angle (AVA) methods are a powerful means of quantifying the physical properties of subglacial material, but serious interpretative errors can arise when AVA is measured over a thinly-layered substrate. A substrate layer with a thickness less than 1/4 of the seismic wavelength, λ, is considered "thin", and reflections from its bounding interfaces superpose and appear in seismic data as a single reflection event. AVA interpretation of subglacial till can be vulnerable to such thin-layer effects, since a lodged (non-deforming) till can be overlain by a thin (metre-scale) cap of dilatant (deforming) till. We assess the potential for misinterpretation by simulating seismic data for a stratified subglacial till unit, with an upper dilatant layer between 0.1–5.0 m thick (λ / 120 to > λ / 4, with λ = 12 m). For dilatant layers less than λ / 6 thick, conventional AVA analysis yields acoustic impedance and Poisson's ratio that indicate contradictory water saturation. A thin-layer interpretation strategy is proposed, that accurately characterises the model properties of the till unit. The method is applied to example seismic AVA data from Russell Glacier, West Greenland, in which characteristics of thin-layer responses are evident. A subglacial till deposit is interpreted, having lodged till (acoustic impedance = 4.26±0.59 × 106 kg m−2 s−1) underlying a water-saturated dilatant till layer (thickness < 2 m, Poisson's ratio ~ 0.5). Since thin-layer considerations offer a greater degree of complexity in an AVA interpretation, and potentially avoid misinterpretations, they are a valuable aspect of quantitative seismic analysis, particularly for characterising till units.

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