Seismic waves from finite faults in layered media

1979 ◽  
Vol 69 (6) ◽  
pp. 1693-1714
Author(s):  
F. Abramovici ◽  
J. Gal-Ezer
Keyword(s):  
Point Source ◽  
Half Space ◽  
Seismic Waves ◽  
Time Dependent ◽  
Homogeneous Layer ◽  
Two Dimensional ◽  
Homogeneous Half Space ◽  
Finite Line ◽  
Finite Line Source ◽  
Time Dependent Solution

abstract The time-dependent solution for a multipolar source in a structure consisting of a homogeneous layer over a homogeneous half-space is obtained as a sum of generalized rays. Numerical seismograms are calculated for a horizontal strikeslip and a horizontal dip-slip for a point-source, a finite line-source, and a finite two-dimensional source in the form of a rectangle. For comparison, the displacements in a homogeneous space and half-space are also calculated. The seismograms for finite sources are similar to those for a point-source but show less conspicuous phases, the arriving pulses being wider and less sharp.

Numerical seismograms obtained using ω-κ integrals, for a point P source in a vertically inhomogeneous anelastic model

1996 ◽  
Vol 86 (3) ◽  
pp. 750-760
Author(s):  
F. Abramovici ◽  
L. H. T. Le ◽  
E. R. Kanasewich
Keyword(s):  
Half Space ◽  
Homogeneous Layer ◽  
Variable Step Size ◽  
Step Size ◽  
Adaptive Process ◽  
Cpu Time ◽  
Homogeneous Half Space ◽  
Linear Layer ◽  
Variable Step ◽  
Viscoelastic Layers

Abstract This article presents some numerical experiments in using a computer program for calculating the displacements due to a P source in a vertically inhomogeneous structure, based on the Fourier-Bessel representation. The structure may contain homogeneous, inhomogeneous, elastic, or viscoelastic layers. The source may act in any type of sublayer or in the half-space. Synthetic results for the simple case of a homogeneous layer overlaying a homogeneous half-space compare favorably with computations based on the Cagniard method. Numerical seismograms for an elastic layer having velocities and density varying linearly with depth were computed by integrating numerically the governing differential systems and compared with results based on the Haskell model of splitting the linear layer in homogeneous sublayers. Even an adaptive process with a variable step size based on the Haskell model has a poorer performance on the accuracy-cpu time scale than numerical integration.

Seismic waves from a horizontal stress discontinuity in a layered solid

1982 ◽  
Vol 72 (5) ◽  
pp. 1483-1498
Author(s):  
F. Abramovici ◽  
E. R. Kanasewich ◽  
P. G. Kelamis
Keyword(s):  
Half Space ◽  
Seismic Waves ◽  
Horizontal Stress ◽  
Radial Component ◽  
Elastic Half Space ◽  
Homogeneous Layer ◽  
Approximate Methods ◽  
Crustal Layer ◽  
Finite Fault ◽  
Stress Discontinuity

abstract The displacement components for a horizontal stress discontinuity along a buried finite fault in an elastic homogeneous layer on top of an elastic half-space are given analytically in terms of generalized rays. For a particular case of a concentrated horizontal force pointing in an arbitrary direction, detailed time-dependent expressions are given. For a simple model of a “crustal” layer over a “mantle” half-space, the numerical seismograms in the near- and intermediate-field show some interesting features. These include a prominent group of compressional waves whose radial component is substantial at distances four times the crustal thickness. All the dominant shear arrivals (s, SS, and sSS) are important and show large variations of amplitude as the source depth and receiver distance are varied. Some of the prominent individual generalized rays are shown, and it is found that they can be grouped naturally into families based on the number of interactions with the boundaries. The subdivision into individual generalized rays is useful for analysis and for checks on the numerical stability of the synthetic seismograms. Since the solution is analytic and the numerical evaluation is complete up to any desired time, the results are useful in comparing other approximate methods for the computation of seismograms.

Inverse source problem based on two dimensionless dispersion-current functions in 2D evolution transport equations

2016 ◽  
Vol 24 (6) ◽  
Author(s):  
Adel Hamdi ◽  
Imed Mahfoudhi
Keyword(s):  
Velocity Field ◽  
Point Source ◽  
Time Dependent ◽  
Inverse Source Problem ◽  
Two Dimensional ◽  
Reaction Equation ◽  
Advection Dispersion ◽  
Dispersion Tensor ◽  
Spatially Varying ◽  
Dependent Point

AbstractThe paper deals with the nonlinear inverse source problem of identifying an unknown time-dependent point source occurring in a two-dimensional evolution advection-dispersion-reaction equation with spatially varying velocity field and dispersion tensor. The

scholarly journals Seismic Waves in a horizontally layered half-space with a general point source

2000 ◽  
Vol 31 (1) ◽  
pp. 19-28
Author(s):  
Hiroshi Takenaka ◽  
Tsutomu Sasatani ◽  
the 210 MM MAGNETIC OBSERVATION GROUP
Keyword(s):  
Point Source ◽  
Half Space ◽  
Seismic Waves ◽  
General Point ◽  
Layered Half Space

Dynamic response of an elastic half-space to time-dependent surface tractions over an embedded spherical cavity

1965 ◽  
Vol 287 (1411) ◽  
pp. 549-567 ◽  
Keyword(s):  
General Solution ◽  
Point Source ◽  
Half Space ◽  
Dynamic Problem ◽  
Spherical Cavity ◽  
Elastic Half Space ◽  
Time Dependent ◽  
Successive Approximations ◽  
Method Of Successive Approximations ◽  
Limit Case

The dynamic problem of the deformation of a homogeneous, perfectly elastic and isotropic half space due to harmonically time-dependent tractions over the boundary of an embedded spherical cavity is discussed. The solution is developed completely and rigorously by a method of successive approximations. Lamb’s solution for a point source in a half-space is derived as a limit case of the general solution. The problem is suggested by its applications in the theory of underground explosions and in seismology.

Ideally conducting magnetostatic equilibria and associated time dependent, resistive flows

1971 ◽  
Vol 6 (1) ◽  
pp. 125-136 ◽  
Author(s):  
John C. Stevenson
Keyword(s):  
Magnetic Field ◽  
Energy Equation ◽  
Incompressible Flows ◽  
Neutral Point ◽  
Time Dependent ◽  
Two Dimensional ◽  
Exact Time ◽  
Field Lines ◽  
Time Dependent Solution ◽  
The Magnetic Field

Several types of two-dimensional solutions for the equations of magnetohydrodynamics are described. For all these solutions the magnetic field contains at least one hyperbolic neutral point. Two new magnetostatic equilibria are introduced for the ideally conducting case. The magnetic field associated with one of these is used to construct an exact time-dependent solution of the MilD equations where the fluid is necessarily at rest. In the case where the field lines are hyperbolae, it is demonstrated that retention of the energy equation (ordinarily decoupled for incompressible flows) implies that the flow beginning at rest, remains at trest

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