Download or read book Supercomputer Finite Difference Methods for Seismic Wave Propagation microform written by Antonios Vafidis and published by National Library of Canada. This book was released on 1988 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Finite Difference Seismic Wave Propagation Using Variable Grid Sizes written by Antonio de Lilla and published by . This book was released on 1997 with total page 236 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Finite difference Method for Seismologists written by Peter Moczo and published by . This book was released on 2004 with total page 150 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Two Dimensional Finite difference Simulation of Seismic Wave Propagation in Elastic Media written by Jeih-San Liow and published by . This book was released on 1988 with total page 404 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Finite difference Modeling of 3D Seismic Wave Propagation in High contrast Media written by and published by . This book was released on 2008 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Serpentine written by and published by . This book was released on 2012 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wave propagation phenomena are important in many DOE applications such as nuclear explosion monitoring, geophysical exploration, estimating ground motion hazards and damage due to earthquakes, non-destructive testing, underground facilities detection, and acoustic noise propagation. There are also future applications that would benefit from simulating wave propagation, such as geothermal energy applications and monitoring sites for carbon storage via seismic reflection techniques. In acoustics and seismology, it is of great interest to increase the frequency bandwidth in simulations. In seismic exploration, greater frequency resolution enables shorter wave lengths to be included in the simulations, allowing for better resolution in the seismic imaging. In nuclear explosion monitoring, higher frequency seismic waves are essential for accurate discrimination between explosions and earthquakes. When simulating earthquake induced motion of large structures, such as nuclear power plants or dams, increased frequency resolution is essential for realistic damage predictions. Another example is simulations of micro-seismic activity near geothermal energy plants. Here, hydro-fracturing induces many small earthquakes and the time scale of each event is proportional to the square root of the moment magnitude. As a result, the motion is dominated by higher frequencies for smaller seismic events. The above wave propagation problems are all governed by systems of hyperbolic partial differential equations in second order differential form, i.e., they contain second order partial derivatives of the dependent variables. Our general research theme in this project has been to develop numerical methods that directly discretize the wave equations in second order differential form. The obvious advantage of working with hyperbolic systems in second order differential form, as opposed to rewriting them as first order hyperbolic systems, is that the number of differential equations in the second order system is significantly smaller. Another issue with re-writing a second order system into first order form is that compatibility conditions often must be imposed on the first order form. These (Saint-Venant) conditions ensure that the solution of the first order system also satisfies the original second order system. However, such conditions can be difficult to enforce on the discretized equations, without introducing additional modeling errors. This project has previously developed robust and memory efficient algorithms for wave propagation including effects of curved boundaries, heterogeneous isotropic, and viscoelastic materials. Partially supported by internal funding from Lawrence Livermore National Laboratory, many of these methods have been implemented in the open source software WPP, which is geared towards 3-D seismic wave propagation applications. This code has shown excellent scaling on up to 32,768 processors and has enabled seismic wave calculations with up to 26 Billion grid points. TheWPP calculations have resulted in several publications in the field of computational seismology, e.g.. All of our current methods are second order accurate in both space and time. The benefits of higher order accurate schemes for wave propagation have been known for a long time, but have mostly been developed for first order hyperbolic systems. For second order hyperbolic systems, it has not been known how to make finite difference schemes stable with free surface boundary conditions, heterogeneous material properties, and curvilinear coordinates. The importance of higher order accurate methods is not necessarily to make the numerical solution more accurate, but to reduce the computational cost for obtaining a solution within an acceptable error tolerance. This is because the accuracy in the solution can always be improved by reducing the grid size h. However, in practice, the available computational resources might not be large enough to solve the problem ...
Download or read book Finite Difference Modelling of Seismic Wave Propagation at the Seafloor written by and published by . This book was released on 1991 with total page 29 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Objectives of this study were (1) to implement the WHOI finite difference code on the CONVEX computer at NORDA and (2) to run a suite of models on the effects of lateral heterogeneity on the primary response from the seafloor. Finite difference solutions to the elastic wave equation accurately predict the response of impulsive and continuous waves sources wave types are included (reflections, refractions, diffractions, Stoneley and pseudo-Rayleigh waves, evanescent waves and head waves). The primary disadvantage of the method is that it is very computation intensive and it is generally limited to problems with dimensions of only a few tens of wavelengths. This can be partially alleviated by using powerful computers such as the CONVEX at NORDA.
Download or read book A Hybrid Method for the Solution of Seismic Wave Propagation Problems written by Arie Pieter van den Berg and published by . This book was released on 1987 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Finite difference simulation of seismic wave propagation in 2D solids with spatial distribution of discrete fractures written by E. Liu and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Spatial Parallelism of a 3D Finite Difference Velocity Stress Elastic Wave Propagation Code written by and published by . This book was released on 1999 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: Finite difference methods for solving the wave equation more accurately capture the physics of waves propagating through the earth than asymptotic solution methods. Unfortunately. finite difference simulations for 3D elastic wave propagation are expensive. We model waves in a 3D isotropic elastic earth. The wave equation solution consists of three velocity components and six stresses. The partial derivatives are discretized using 2nd-order in time and 4th-order in space staggered finite difference operators. Staggered schemes allow one to obtain additional accuracy (via centered finite differences) without requiring additional storage. The serial code is most unique in its ability to model a number of different types of seismic sources. The parallel implementation uses the MP1 library, thus allowing for portability between platforms. Spatial parallelism provides a highly efficient strategy for parallelizing finite difference simulations. In this implementation, one can decompose the global problem domain into one-, two-, and three-dimensional processor decompositions with 3D decompositions generally producing the best parallel speed up. Because i/o is handled largely outside of the time-step loop (the most expensive part of the simulation) we have opted for straight-forward broadcast and reduce operations to handle i/o. The majority of the communication in the code consists of passing subdomain face information to neighboring processors for use as ''ghost cells''. When this communication is balanced against computation by allocating subdomains of reasonable size, we observe excellent scaled speed up. Allocating subdomains of size 25 x 25 x 25 on each node, we achieve efficiencies of 94% on 128 processors. Numerical examples for both a layered earth model and a homogeneous medium with a high-velocity blocky inclusion illustrate the accuracy of the parallel code.
Download or read book Numerical Modeling of Seismic Wave Propagation written by Johan O. A. Robertsson and published by . This book was released on 2012 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Making and Propagating Elastic Waves written by and published by . This book was released on 2006 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: We are developing a new parallel 3D wave propagation code at LLNL called WPP (Wave Propagation Program). WPP is being designed to incorporate the latest developments in embedded boundary and mesh refinement technology for finite difference methods, as well as having an efficient portable implementation to run on the latest supercomputers at LLNL. We are currently exploring seismic wave applications, including a recent effort to compute ground motions for the 1906 Great San Francisco Earthquake. This paper will briefly describe the wave propagation problem, features of our numerical method to model it, implementation of the wave propagation code, and results from the 1906 Great San Francisco Earthquake simulation.
Download or read book Numerical Modeling of Linear and Nonlinear Seismic Wave Attenuation written by and published by . This book was released on 1998 with total page 81 pages. Available in PDF, EPUB and Kindle. Book excerpt: CTBT verification requires an understanding of the propagation of seismic phases over complex regional paths which cut across major structural boundaries. The computation of synthetic seismograms by finite difference methods plays an important role in developing such understanding. In order for synthetic seismograms to be realistic, the models must account not only for regional elastic structure of the path, but also for an elastic losses. In addition, high amplitudes near the source require that numerical models take account of nonlinearity. Heretofore, 3D finite difference simulations have generally neglected attenuation, due in large part to the onerous storage requirements entailed by realistic seismic Q models. We describe a novel solution to this problem which we call memory-variable coarse-graining. The coarse-graining method leads to an order of magnitude reduction in computer storage requirements for an elastic memory variables. We then develop and demonstrate a method for modeling nonlinear wave propagation in rock under conditions of intermediate strain, defined as strain levels below the threshold for failure and damage, but above the threshold for onset of nonlinear response. The resulting model reproduces the stress-strain behavior of rock in this strain regime, as measured in quasi-static laboratory tests, and is consistent with key features of laboratory wave propagation measurements.
Download or read book A Three dimensional Finite Element Method to Elastic Wave Propagation in Strong Ground Motion written by Minh N. Tran and published by . This book was released on 2011 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: There are mainly four types of waves in elastic wave propagation during an earthquake: P- (pressure or primary), S- (shear or secondary), Love, and Rayleigh waves. P- and S-waves are body waves traveling through the interior of the earth. As body waves reach the earth surface they become surface waves: Love and Rayleigh waves, which are responsible for damage and destruction associated with earthquake. In this thesis, these four types of waves are studied and modeled. The semi-discrete numerical scheme used to conduct simulation for these waves is the finite element method which is continuous in space and the finite difference method which is discrete in time. Finally, a simple case of earthquake, where a seismic wave propagates from the source through the soil medium along the fault path to the surface, is investigated.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 568 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Finite Difference Modelling of Earthquake Motions written by Peter Moczo and published by . This book was released on 2014-05-10 with total page 388 pages. Available in PDF, EPUB and Kindle. Book excerpt: A systematic tutorial introduction to the finite-difference (FD) numerical modelling technique for professionals, academic researchers, and graduate students in seismology.
