Strong ground motion from point sources
Abstract
Analytic expressions are obtained for the surface displacements of an idealized layered flat earth produced by elementary point sources. The integral expressions are put into form more tractable to numerical evaluation. The orientation of the fault and slip vectors is factored from the solution, the total displacement field for a given layered system source depth, and epicentral distance is given by a linear superposition of eight modal components. A computer program to calculate the body wave portion of the displacement field is described and a listing provided. Realistic values of the parameters are used in the numerical examples. A measure of finiteness is incorporated into the source by integrating the source time dependence over a hypothetical circular fault. The significance of a few of the approximations and uncertainties inherent to the field of earthquake engineering were examined via parametric variation. The time domain displacements and velocities obtained are plausible and exhibit features similar to recorded motions. Results indicate that the motions are more sensitive to variations at the site, i.e. layering, than to variations at the source, i.e. fault parameters, source depth, and epicentral distance. The incorporation of layering was found to be much more important than the accurate determination of the layer parameters.
 Publication:

Ph.D. Thesis
 Pub Date:
 1978
 Bibcode:
 1978PhDT........57H
 Keywords:

 Numerical Analysis;
 Point Sources;
 Surface Distortion;
 Approximation;
 Computer Programs;
 Displacement;
 Earthquakes;
 Geological Faults;
 Time Dependence;
 Variations;
 Vectors (Mathematics);
 Velocity Distribution;
 Geophysics