Seismic waves in medium with poroelastic/elastic interfaces: a two-dimensional P-SV finite-difference modelling

2021 ◽  
Vol 228 (1) ◽  
pp. 551-588
Author(s):  
David Gregor ◽  
Peter Moczo ◽  
Jozef Kristek ◽  
Arnaud Mesgouez ◽  
Gaëlle Lefeuve-Mesgouez ◽  
...  
Keyword(s):  
Finite Difference ◽  
Seismic Waves ◽  
Heterogeneous Medium ◽  
Spectral Element ◽  
Seismic Wave Propagation ◽  
Material Interfaces ◽  
Material Interface ◽  
Frequency Dependent ◽  
Arbitrary Position ◽  
Elastic Interfaces

SUMMARY We present a new methodology of the finite-difference (FD) modelling of seismic wave propagation in a strongly heterogeneous medium composed of poroelastic (P) and (strictly) elastic (E) parts. The medium can include P/P, P/E and E/E material interfaces of arbitrary shapes. The poroelastic part can be with (i) zero resistive friction, (ii) non-zero constant resistive friction or (iii) JKD model of the frequency-dependent permeability and resistive friction. Our FD scheme is capable of subcell resolution: a material interface can have an arbitrary position in the spatial grid. The scheme keeps computational efficiency of the scheme for a smoothly and weakly heterogeneous medium (medium without material interfaces). Numerical tests against independent analytical, semi-analytical and spectral-element methods prove the efficiency and accuracy of our FD modelling. In numerical examples, we indicate effect of the P/E interfaces for the poroelastic medium with a constant resistive friction and medium with the JKD model of the frequency-dependent permeability and resistive friction. We address the 2-D P-SV problem. The approach can be readily extended to the 3-D problem.

Subcell-resolution finite-difference modelling of seismic waves in Biot and JKD poroelastic media

2020 ◽  
Vol 224 (2) ◽  
pp. 760-794
Author(s):  
David Gregor ◽  
Peter Moczo ◽  
Jozef Kristek ◽  
Arnaud Mesgouez ◽  
Gaëlle Lefeuve-Mesgouez ◽  
...  
Keyword(s):  
Finite Difference ◽  
Ground Motion ◽  
Seismic Waves ◽  
Heterogeneous Medium ◽  
Seismic Wave Propagation ◽  
Earthquake Ground Motion ◽  
Material Interfaces ◽  
Frequency Dependent ◽  
Poroelastic Media ◽  
Efficiency And Reliability

SUMMARY We present a discrete representation of strongly heterogeneous poroelastic medium with the JKD-model of the frequency-dependent permeability and resistive friction, and the corresponding finite-difference (FD) scheme for numerical modelling of seismic wave propagation and earthquake ground motion in structurally complex media. The scheme is capable of subcell resolution, that is, allows for an arbitrary shape and position of an interface in the spatial grid. The medium can have either a zero resistive friction or non-zero constant resistive friction or JKD frequency-dependent resistive friction. The scheme has the same computational efficiency as the scheme for a smoothly and weakly heterogeneous medium (medium without material interfaces) because the number of operations for updating wavefield is the same. Several comparisons with a semi-analytical approach proves the efficiency and reliability of the subcell-resolution FD scheme. An illustrative example demonstrates differences between earthquake ground motion in the Biot's and JKD variants of the model of the surface sedimentary basin. The example indicates that it is desirable to perform an extensive parametric study in order to find out when it is necessary to apply relatively complicated and computationally more demanding JKD model and when much simpler Biot's model is sufficient.

scholarly journals 2D full-waveform modeling of seismic waves in layered karstic media

Geophysics ◽  
2016 ◽  
Vol 81 (2) ◽  
pp. T25-T34 ◽  
Author(s):  
Yingcai Zheng ◽  
Adel H. Malallah ◽  
Michael C. Fehler ◽  
Hao Hu
Keyword(s):  
Seismic Waves ◽  
Finite Size ◽  
Spectral Element ◽  
Seismic Wave Propagation ◽  
Complex Model ◽  
Waveform Modeling ◽  
Frequency Space ◽  
Full Waveform ◽  
Matrix Scheme ◽  
Element Method

We have developed a new propagator-matrix scheme to simulate seismic-wave propagation and scattering in a multilayered medium containing karstic voids. The propagator matrices can be found using the boundary element method. The model can have irregular boundaries, including arbitrary free-surface topography. Any number of karsts can be included in the model, and each karst can be of arbitrary geometric shape. We have used the Burton-Miller formulation to tackle the numerical instability caused by the fictitious resonance due to the finite size of a karstic void. Our method was implemented in the frequency-space domain, so frequency-dependent [Formula: see text] can be readily incorporated. We have validated our calculation by comparing it with the analytical solution for a cylindrical void and to the spectral element method for a more complex model. This new modeling capability is useful in many important applications in seismic inverse theory, such as imaging karsts, caves, sinkholes, and clandestine tunnels.

scholarly journals Deep learning for fast simulation of seismic waves in complex media

Solid Earth ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 1527-1549 ◽  
Author(s):  
Ben Moseley ◽  
Tarje Nissen-Meyer ◽  
Andrew Markham
Keyword(s):  
Deep Learning ◽  
Finite Difference ◽  
Seismic Response ◽  
Network Architecture ◽  
Seismic Waves ◽  
Computational Cost ◽  
Seismic Source ◽  
Spectral Element ◽  
Seismic Inversion ◽  
Order Of Magnitude

Abstract. The simulation of seismic waves is a core task in many geophysical applications. Numerical methods such as finite difference (FD) modelling and spectral element methods (SEMs) are the most popular techniques for simulating seismic waves, but disadvantages such as their computational cost prohibit their use for many tasks. In this work, we investigate the potential of deep learning for aiding seismic simulation in the solid Earth sciences. We present two deep neural networks which are able to simulate the seismic response at multiple locations in horizontally layered and faulted 2-D acoustic media an order of magnitude faster than traditional finite difference modelling. The first network is able to simulate the seismic response in horizontally layered media and uses a WaveNet network architecture design. The second network is significantly more general than the first and is able to simulate the seismic response in faulted media with arbitrary layers, fault properties and an arbitrary location of the seismic source on the surface of the media, using a conditional autoencoder design. We test the sensitivity of the accuracy of both networks to different network hyperparameters and show that the WaveNet network can be retrained to carry out fast seismic inversion in the same media. We find that are there are challenges when extending our methods to more complex, elastic and 3-D Earth models; for example, the accuracy of both networks is reduced when they are tested on models outside of their training distribution. We discuss further research directions which could address these challenges and potentially yield useful tools for practical simulation tasks.

Localization of Rockfalls at Dolomieu Crater, La Réunion, through Simulation of Seismic Waves on Real Topography

2020 ◽  
Author(s):  
Julian Kuehnert ◽  
Anne Mangeney ◽  
Yann Capdeville ◽  
Emmanuel Chaljub ◽  
Eleonore Stutzmann ◽  
...  
Keyword(s):  
Impulse Response ◽  
Seismic Waves ◽  
Time Window ◽  
Specific Area ◽  
Velocity Model ◽  
Seismic Signal ◽  
Spectral Element ◽  
Seismic Wave Propagation ◽  
Location Estimation ◽  
Energy Ratios

<p>Rockfall generated seismic signals have been shown to be of great utility in order to detect and monitor rockfall activity. Furthermore, event locations were successfully estimated using methods which rely on either arrival times, amplitudes or polarization of the seismic signal. However, strong surface topography can significantly influence seismic wave propagation and thus flaw the estimates if not taken into account correctly.</p><p>On the upside, the imprint of topography on the seismic signal can be characteristic of the source position. We show that this additional information can be used to get a more detailed rockfall location estimation. In order to do so, the seismic impulse response is modeled on a domain with 3D topography using the Spectral Element Method. Subsequently, in order to locate events, station energy ratios of the synthetic seismograms are compared with energy ratios of rockfall signals in a sliding time window.</p><p>We test the method on rockfalls which occurred at Dolomieu crater of Piton de la Fournaise, La Réunion. The sensitivity of the method on the resolution of the modeled topography and the underlying velocity model is tested. We propose that the method can be applied for monitoring rockfall activity in a specific area with multiple seismic stations after calculating once the impulse response for the corresponding topography.</p>

scholarly journals 3D adaptive internal multiples modeling based on globally optimised Fourier finite-difference method

2021 ◽  
Vol 18 (4) ◽  
pp. 429-445
Author(s):  
Jiandong Huang ◽  
Tianyue Hu ◽  
Chenghong Zhu ◽  
Zhefeng Wei ◽  
Fei Xie ◽  
...  
Keyword(s):  
Finite Difference ◽  
Seismic Waves ◽  
Simulation Method ◽  
Seismic Wave Propagation ◽  
Modeling Technique ◽  
Superior Performance ◽  
Multiple Reflections ◽  
Lateral Velocity ◽  
Internal Multiples ◽  
Different Order

Abstract Numerical methods have been widely applied to simulate seismic wave propagation. However, few studies have focused on internal multiples modeling. The formation mechanism and response of internal multiples are still unclear. Therefore, we develop a weighted-optimised-based internal multiples simulation method under 3D conditions. Using a one-way wave equation and full-wavefield method, the different-order internal multiples are computed numerically in a recursive manner. The traditional Fourier finite-difference (FFD) method has low numerical accuracy in a horizontal direction. A globally optimised FFD (OFFD) method is used to improve the lateral propagation accuracy of the seismic waves. Meanwhile, we adopt an adaptive variable-step technique to improve computational efficiency. The 3D internal multiples modeling technique is capable of calculating the different-order multiple reflections in complex structures. We use the present method to simulate internal multiples in several models. Theoretical analyses are consistent with the numerical results. Numerical examples demonstrate that the 3D internal multiples modeling technique has superior performance when adapting to lateral velocity changes and steep dip. This also implies that our method is fit for the simulation of internal multiples propagation in a 3D complex medium and can assist in identifying the internal multiples from full-wavefield data.

scholarly journals Numerical modeling of seismic waves by discontinuous spectral element methods

2018 ◽  
Vol 61 ◽  
pp. 1-37 ◽  
Author(s):  
Paola F. Antonietti ◽  
Alberto Ferroni ◽  
Ilario Mazzieri ◽  
Roberto Paolucci ◽  
Alfio Quarteroni ◽  
...  
Keyword(s):  
Numerical Modeling ◽  
Discontinuous Galerkin ◽  
Large Scale ◽  
Seismic Waves ◽  
Spectral Element ◽  
Fully Discrete ◽  
Time Marching ◽  
Space Discretization ◽  
Large Earthquakes

We present a comprehensive review of Discontinuous Galerkin Spectral Element (DGSE) methods on hybrid hexahedral/tetrahedral grids for the numerical modeling of the ground motion induced by large earthquakes. DGSE methods combine the exibility of discontinuous Galerkin meth-ods to patch together, through a domain decomposition paradigm, Spectral Element blocks where high-order polynomials are used for the space discretization. This approach allows local adaptivity on discretization parameters, thus improving the quality of the solution without affecting the compu-tational costs. The theoretical properties of the semidiscrete formulation are also revised, including well-posedness, stability and error estimates. A discussion on the dissipation, dispersion and stability properties of the fully-discrete (in space and time) formulation is also presented. Here space dis-cretization is obtained based on employing the leap-frog time marching scheme. The capabilities of the present approach are demonstrated through a set of computations of realistic earthquake scenar-ios obtained using the code SPEED (http://speed.mox.polimi.it), an open-source code specifically designed for the numerical modeling of large-scale seismic events jointly developed at Politecnico di Milano by The Laboratory for Modeling and Scientific Computing MOX and by the Department of Civil and Environmental Engineering.

Three-Dimensional Simulations of Strong Ground Motion in the Shidian Basin

2014 ◽  
Vol 501-504 ◽  
pp. 1447-1452
Author(s):  
Yan Yan Yu ◽  
Qi Fang Liu
Keyword(s):  
Surface Wave ◽  
Ground Motion ◽  
Seismic Waves ◽  
Three Dimensional ◽  
Spectral Element ◽  
Low Velocity ◽  
Computing Technique ◽  
Soil Deposits ◽  
Basin Edge ◽  
The Impact

Seismic response of the Shidian basin to moderate scenario earthquake is investigated considering 3D basin model incorporated with real topography by using the spectral-element method and parallel computing technique. The wave propagation process, the generation of surface wave, and the impact of soil deposits velocity to the basin-induced surface wave are studied in this paper. The results show that the amplification behavior of the basin is the interactions of basin geometry and low velocity soil deposits. First, locally small hollows in the basin are apt to trap seismic waves and produce much stronger ground motion, basin edge and areas with deep sediments are also characterized with large amplification. Then, basin with softer soil deposits produces stronger surface waves with lower propagation velocity and higher mode.

scholarly journals Seismic wave propagation in anisotropic ice – Part 1: Elasticity tensor and derived quantities from ice-core properties

2015 ◽  
Vol 9 (1) ◽  
pp. 367-384 ◽  
Author(s):  
A. Diez ◽  
O. Eisen
Keyword(s):  
Seismic Waves ◽  
Dynamic Behaviour ◽  
Ice Core ◽  
Ice Cores ◽  
Seismic Wave Propagation ◽  
Elasticity Tensor ◽  
Reflection Coefficients ◽  
Seismic Velocities ◽  
Crystal Anisotropy ◽  
Elasticity Tensors

Abstract. A preferred orientation of the anisotropic ice crystals influences the viscosity of the ice bulk and the dynamic behaviour of glaciers and ice sheets. Knowledge about the distribution of crystal anisotropy is mainly provided by crystal orientation fabric (COF) data from ice cores. However, the developed anisotropic fabric influences not only the flow behaviour of ice but also the propagation of seismic waves. Two effects are important: (i) sudden changes in COF lead to englacial reflections, and (ii) the anisotropic fabric induces an angle dependency on the seismic velocities and, thus, recorded travel times. A framework is presented here to connect COF data from ice cores with the elasticity tensor to determine seismic velocities and reflection coefficients for cone and girdle fabrics. We connect the microscopic anisotropy of the crystals with the macroscopic anisotropy of the ice mass, observable with seismic methods. Elasticity tensors for different fabrics are calculated and used to investigate the influence of the anisotropic ice fabric on seismic velocities and reflection coefficients, englacially as well as for the ice–bed contact. Hence, it is possible to remotely determine the bulk ice anisotropy.

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