| Abstract: | The frequency characteristics of near-surface sediments obtained from small scale S-wave refraction measurements conducted at two sites in the Garf Hussein area, contiguous to the High Dam Lake, South of Aswan, have shown drastic changes in the frequency-selective amplification of horizontal ground motion within a relatively short surface distance. This effect is attributed mainly to such factors as the variation in layer thickness and the presence or absence of soft alluvial deposits.These results indicate that movements initiated deep in the earth's crust may not be faithfully reflected on the ground surface. As geodetic work principally involves monitoring relative horizontal and vertical displacements on the earth's surface with time, geodesists are advised to take the spectral response of the ground into consideration. |
