Full text loading...
-
IN PURSUIT OF THE ERRANT SEISMIC PULSE*
- Source: Geophysical Prospecting, Volume 10, Issue 2, Apr 1962, p. 148 - 163
-
- 27 Apr 2006
Abstract
The results obtained from a series of geophones extending vertically from the surface down to a particularly strong reflector 450 m deep have provided an insight into the properties of the various types of wave generated by an explosion in the ground and have shown how these waves are converted into other types near the surface and at a reflector. The direct shear pulse generated by an explosion was observed to be quite simple and to penetrate to the deepest geophone even from large horizontal distances, but to be much more attenuated and broadened on its way through the earth than the compressional pulse. This shear pulse was found to be the cause of the ground‐roll commonly observed at the surface. A clear PS reflection, of the same magnitude as the PP reflection, was observed from the reflector 450 m deep. This shear event starts out from the reflector as a short and simple pulse, but does not persist as such on its way to the surface. It loses its sharpness well before reaching the base of the weathered layer, whereas the reflected compressional pulse is hardly affected at all.