Dynamic rupture in a layered medium: The 1966 Parkfield earthquake

1980 ◽  
Vol 70 (3) ◽  
pp. 671-689
Author(s):  
Ralph J. Archuleta ◽  
Steven M. Day
Keyword(s):  
Wave Propagation ◽  
Stress Relaxation ◽  
Ground Motion ◽  
Layered Medium ◽  
Heterogeneous Medium ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Dynamic Rupture ◽  
Time Histories ◽  
Parkfield Earthquake

abstract A method for computing ground motion from a propagating stress relaxation in a vertically heterogeneous medium was developed wherein computational efficiency is enhanced by separating the source, a three-dimensional calculation, from the wave propagation, a two-dimensional calculation. As an application of this technique, displacement-time histories were computed corresponding to those determined from accelerograms recorded during the 1966 Parkfield, California earthquake. On the basis of these comparisons, an effective stress of 25 bars, an average slip of 43 cm, and a moment of 2.32 × 1025 dyne-cm were determined for the Parkfield earthquake.

Love-wave propagation in a three-dimensional sedimentary basin

1992 ◽  
Vol 82 (4) ◽  
pp. 1661-1677 ◽  
Author(s):  
Takumi Toshinawa ◽  
Tatsuo Ohmachi
Keyword(s):  
Finite Element ◽  
Wave Propagation ◽  
Love Wave ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Sedimentary Basins ◽  
Two Dimensional ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Time Histories

Abstract A simplified three-dimensional finite-element method has been developed for simulation of Love-wave propagation in three-dimensional sedimentary basins. The eigenfunctions for the fundamental-mode surface waves are employed as interpolation functions in the finite-element scheme. By reducing the number of degrees of freedom, the method enables us to analyze wave propagation in an area of 2000 km2 as large as the southern part of the Kanto plain, Japan. Time histories of the near Izu-Ohshima earthquake of 1990 are calculated and compared with observation. Calculated displacement snapshots show the effect of three-dimensional topography on direction of Love-wave propagation. The three-dimensional simulation is also compared with a two-dimensional one, demonstrating amplitude increase and extended duration. Time histories and their spectra from the three-dimensional model show better agreement with the observations than those from the two-dimensional model.

Eclectic modelling of the North Atlantic. II. Transient tracers and the ventilation of the Eastern Basin thermocline

1988 ◽  
Vol 325 (1583) ◽  
pp. 201-236 ◽  
Keyword(s):  
North Atlantic ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Ekman Pumping ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Oxygen Utilization ◽  
The North ◽  
Time Histories ◽  
Weak Constraints

Renewal rates of the waters of the thermocline in the eastern North Atlantic are estimated by combining linear quasi-geostrophic dynamics with steady and transient tracers into a unified eclectic, reservoir model. The two-dimensional model first employed is finally rejected when it is found that it generates oxygen-utilization rates (OUR) that are, by conventional biological wisdom, too high. The three-dimensional model that replaces the two-dimensional one shows that the our is indeterminate, with possible ranges from zero to unacceptably high values. The region is flushed primarily from the north and east. The problem of using transient tracers is mathematically equivalent to that of distributed-system boundary-control theory, the open-ocean boundary conditions playing the role of the unknown control variables. The missing time histories of this new set of unknowns means that tritium and helium-3 distributions are only comparatively weak constraints on the flow field, but do set upper bounds on the vertical exchange with surface waters. Surface Ekman pumping is adequate to explain the interior distributions without additional buoyancy ventilation, although this latter process is possible. Some speculation is made about conditions under which transient tracers might play a more definitive role.

2.5D AND 3D GREEN'S FUNCTIONS FOR ACOUSTIC WEDGES: IMAGE SOURCE TECHNIQUE VERSUS A NORMAL MODE APPROACH

2013 ◽  
Vol 21 (01) ◽  
pp. 1250025 ◽  
Author(s):  
A. TADEU ◽  
E. G. A. COSTA ◽  
J. ANTÓNIO ◽  
P. AMADO-MENDES
Keyword(s):  
Wave Propagation ◽  
Normal Mode ◽  
Green's Functions ◽  
Green’S Functions ◽  
Three Dimensional ◽  
Element Formulation ◽  
Two Dimensional ◽  
Image Source ◽  
Point Pressure ◽  
Fluid Channel

2.5D and 3D Green's functions are implemented to simulate wave propagation in the vicinity of two-dimensional wedges. All Green's functions are defined by the image-source technique, which does not account directly for the acoustic penetration of the wedge surfaces. The performance of these Green's functions is compared with solutions based on a normal mode model, which are found not to converge easily for receivers whose distance to the apex is similar to the distance from the source to the apex. The applicability of the image source Green's functions is then demonstrated by means of computational examples for three-dimensional wave propagation. For this purpose, a boundary element formulation in the frequency domain is developed to simulate the wave field produced by a 3D point pressure source inside a two-dimensional fluid channel. The propagating domain may couple different dipping wedges and flat horizontal layers. The full discretization of the boundary surfaces of the channel is avoided since 2.5D Green's functions are used. The BEM is used to couple the different subdomains, discretizing only the vertical interfaces between them.

scholarly journals Loading on a Rigid Target from Close Proximity Underwater Explosions

2012 ◽  
Vol 19 (4) ◽  
pp. 555-571 ◽  
Author(s):  
Mark Riley ◽  
Malcolm Smith ◽  
J.E. van Aanhold ◽  
Niklas Alin
Keyword(s):  
Three Dimensional ◽  
Computational Effort ◽  
Bubble Collapse ◽  
Time Of Arrival ◽  
Gas Bubble ◽  
Two Dimensional ◽  
Underwater Explosions ◽  
Close Proximity ◽  
Time Histories ◽  
Three Dimensional Simulations

The study describes recent simulation results for underwater explosions in close-proximity to rigid targets. Simulations are performed using Chinook, an Eulerian computational fluid dynamics (CFD) code. Predicted target loadings are compared with measurements taken from a series of experiments conducted under an international collaboration between Canada, The Netherlands, and Sweden. The simulations of the rigid target tests focused on the modelling of gas bubble collapse and water jetting behaviour. Both two-dimensional and three-dimensional simulations were performed. It was found that the two-dimensional analyses produced good bubble periods and reasonable impulse loading compared to experimental data. The time of arrival of the bubble collapse and water jetting were found to be very mesh dependent and refining the mesh did not always produce better results. The two-dimensional approach provides a good initial understanding of the problem for a reasonable computational effort. The three-dimensional simulations were found to produce improved impulse predictions. The numerical gas bubble radii time histories are also compared to empirical time histories.

Two-Dimensional Simulation of Wave Propagation in a Three-Pipe Junction

2000 ◽  
Vol 122 (4) ◽  
pp. 549-555 ◽  
Author(s):  
R. J. Pearson ◽  
M. D. Bassett ◽  
P. Batten ◽  
D. E. Winterbone
Keyword(s):  
Wave Propagation ◽  
Adaptive Mesh Refinement ◽  
Adaptive Mesh ◽  
Finite Volume Scheme ◽  
Two Dimensional ◽  
Action Simulation ◽  
Pressure Time ◽  
Time Histories ◽  
Dimensional Simulation ◽  
Measured Pressure

The modelling of wave propagation in complex pipe junctions is one of the biggest challenges for simulation codes, particularly those applied to flows in engine manifolds. In the present work an inviscid two-dimensional model, using an advanced numerical scheme, has been applied to the simulation of shock-wave propagation through a three-pipe junction; the results are compared with corresponding schlieren images and measured pressure-time histories. An approximate Riemann solver is used in the shock-capturing finite volume scheme and the influence of the order of accuracy of the solver and the use of adaptive mesh refinement are investigated. The code can successfully predict the evolution and reflection of the wave fronts at the junctions whilst the run time is such as to make it feasible to include such a model as a local multi-dimensional region within a one-dimensional wave-action simulation of flow in engine manifolds. [S0742-4795(00)01304-1]

The Whittier Narrows, California Earthquake of October 1, 1987—Note on Peak Accelerations during the 1 and 4 October Earthquakes

1988 ◽  
Vol 4 (1) ◽  
pp. 101-113 ◽  
Author(s):  
M. D. Trifunac
Keyword(s):  
Wave Propagation ◽  
Los Angeles ◽  
Ground Motion ◽  
Strong Ground Motion ◽  
Strong Dependence ◽  
Three Dimensional ◽  
Physical Processes ◽  
Los Angeles Basin ◽  
Dense Arrays ◽  
Strong Ground

Attenuation patterns of the recorded peak accelerations during two moderate earthquakes (ML = 5.9 and 5.3) in Los Angeles, California are described. It is shown that the recording of earthquake motions by dense arrays of accelerographs can yield a detailed and deterministic picture of the physical processes which are involved in shaping the observed variations of strong ground motion. For the two earthquakes the observed changes of peak amplitudes with respect to the azimuth and distance are slowly and continuously changing functions showing strong dependence of amplitudes on the radiation patterns of the two earthquakes and on the effects of wave propagation through irregular three-dimensional geology of the Los Angeles basin.

The relationship between two- and three-dimensional elastic-wave propagation

1971 ◽  
Vol 61 (6) ◽  
pp. 1583-1588 ◽  
Author(s):  
C. N. G. Dampney
Keyword(s):  
Wave Propagation ◽  
Elastic Wave ◽  
Three Dimensional ◽  
Elastic Wave Propagation ◽  
Simple Relationship ◽  
Two Dimensional ◽  
Intrinsic Interest ◽  
Cylindrically Symmetric ◽  
The Relationship ◽  
Dimensional Wave

abstract A technique similar to inverting Abel's equation is used to invert the descent of dimensions method between three-dimensional, cylindrically-symmetric and two-dimensional wave propagation. The end result is a very simple relationship between the two types of wave propagation. Apart from its intrinsic interest, the large number of two-dimensional studies reported in the literature could now be related to their three-dimensional counterparts.

Wave Propagation and Attenuation in Piping Systems

1986 ◽  
Vol 108 (4) ◽  
pp. 441-446 ◽  
Author(s):  
Shiran Nanayakkara ◽  
N. Duke Perreira
Keyword(s):  
Wave Propagation ◽  
Three Dimensional ◽  
Piping System ◽  
Transmission Matrix ◽  
Two Dimensional ◽  
Longitudinal Vibrations ◽  
Bending Vibrations ◽  
Piping Systems ◽  
Modes Of Vibration ◽  
Computational Errors

Results of an investigation on wave propagation in two-dimensional fluid-filled piping systems is reported. This phenomenon is studied by first developing a model for the transmission of solid-borne and fluid-borne vibrations in fluid-filled piping system elements, such as bends and straight sections. The aforementioned model, which is represented by an element transmission matrix, is used to determine the transfer and point impedances between the motion and forces of both the pipe and the fluid at any point within the element. It allows for longitudinal vibrations in the fluid, and longitudinal and bending vibrations in the solid portion of the system. The effects of both shear strains and rotary inertia within the pipe are included, while the effects of fluid flow and radial or angular modes in the fluid are neglected. Computer results for two-dimensional piping systems with modes of vibration in the plane of the pipes are considered. This method which is exact, except for possible computational errors, can be easily extended to the three-dimensional case.

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