Radiation Of Surface Waves Research Articles

A perturbation method for the radiation of short surface waves in three dimensions

This paper is an extension of an earlier paper ([1]) on the subject of the radiation of waves by a heaving circular cylinder in two-dimensions. In this paper the same ideas of boundary layer expansions are employed and extended to the general three-dimensional case. The ray method is used to extend the solution from a locally two-dimensional solution to the general far field solution. In the case that caustics occur, a uniform method is described to avoid solutions which become locally non-valid.

A perturbation method for the radiation of surface waves

In this paper we derive a straight forward asymptotic method to find the wave solution for the case that a circular cylinder is heaving in a free surface. The wave period is supposed to be small. The methods used are similar to methods used in the theory of geometrical optics and the theory of boundary layer expansions. It turns out that not only the lowest order approximation can be easily calculated, higher order approximations follow as well.

Radiation and scattering of water waves by rigid bodies

Schwinger's variational formulation is applied to the radiation of surface waves due to small oscillation of bodies. By means of Haskind's theorem the wave forces on a stationary body due to a plane incident wave are found using only far-field properties. Results for horizontal rectangular and vertical circular cylinders are presented.

The Alaska Earthquake of 1964: Radiation of long-period surface waves and source mechanism

The records of multiple Love and Rayleigh waves of the Alaska earthquake of 1964 were recovered from the 30–100 seismograph records at the WWSSN stations. The seismograms were equalized to a propagation distance of 9π/2 (equivalent to G5 and R5 at Δ = π/2). These seismograms were compared with synthetic seismograms for radiation pattern and amplitude to estimate various source parameters. The synthetic seismograms were computed from the normal mode solutions. One simple, yet plausible, source model was found. The nature of the fault is essentially that of a low-angle thrust faulting. The direction of rupture propagation does not coincide with the strike of the fault. This enables one to distinguish between the fault plane and the auxiliary plane. The source parameters determined are as follows: force system, double couple, reverse dip slip; fault plane, dip angle 20°, dip direction N 24°W; rupture length. 600 km; rupture velocity, 3.5 km/sec towards S25°W; moment, 7.5×10^(29) dyne-cm; average slip dislocation, 7 meters in N24°W direction; stress drop, 28 bars; strain drop, 0.4×10^(−4); released strain energy. 1.5×10^(25) ergs. The moment and the width of the fault plane of this earthquake are much larger than those of any other earthquakes reported.

Radiation of seisimic surface waves from extending circular sources

abstract The radiation of Rayleigh and Love waves from two different horizontal circular sources of stress is studied. The displacement on the free surface is deduced from the equations of motion and boundary conditions and then integrated over a finite radius to simulate a disturbance extending with a constant finite velocity.

On the Radiation of Short Surface Waves By a Finite Dock

On the Radiation of Short Surface Waves By a Finite Dock

A Quantitative Evaluation of Seismic Signals at Teleseismic Distances?I Radiation from Point Sources

Summary The aim of the series of papers to be published under the above title is to follow up and improve Carpenter's (1966) attempt to construct realistic pulse shapes for teleseismic body waves from underground explosions. The present work deals with both explosions and shallow earthquakes and with the radiation of surface waves as well as body waves. The extension of Carpenter's theory to take crustal layering more accurately into account involves the matrix theory first introduced by Thomson (1950) and developed by Haskell. We shall use the notation of Haskell's (1964) paper in the following analysis and the initial theoretical work is concerned with some of the groundwork and one or two results which have not been covered by Haskell in his series of papers (1953, 1962, 1964). A point source can be represented either as a system of forces or as a discontinuity in the displacement or stress or their derivatives across an element of surface. We show here that a general source of either type is equivalent in the generation of elastic radiation to a discontinuity across a horizontal plane in the displacement and the stress acting on the plane. This means that any point source can be put into a form suitable for computations based on the Thomson-Haskell theory. The theory is applied to the construction of theoretical models of earthquake and explosive sources. Some of the more realistic models so far proposed are given in the later section of the paper.

The radiation and diffraction of surface waves from a vertically floating plate

The simplest plane problem connected with the hydrodynamics of wave motion of ships is dealt with in this article, namely the oscillation of a plate floating vertically in a disturbed heavy liquid of infinite depth. The problem is solved in “closed” form and the solution is obtained by the same methods as employed in the case of pure diffraction [1]. Exact values are obtained for general coefficients of damping and mass couping, in terms of cylindrical functions. Formulas are direved giving mean values of the hydrodynamic forces over a cycle of oscillation in the form of a quadratic approximation.