Development of a continous signal seismic system for high resolution applications.

摘要

A continuous signal seismic system for high resolution applications was developed and field tested; the resulting seismic data were compared to those acquired using hammer and shot gun sources. As a further part of this investigation. techniques were developed to measure receiver response characteristics in the laboratory and receiver-earth coupling in the field.;A vibrational transducer was employed as the source. In addition to a short auger, a long auger and baseplate were tested as source coupling devices. Excitation of the source was accomplished using a sound card for a personal computer, an audio amplifier and software developed by the author.;Both cosine-tapered linear swept sinusoids and pseudo-random sequences of maximal length were used as excitation signals. A number of important parameters were varied in both the excitation and recording of the data to determine the best ones to use. These parameters included: signal bandwidth and centre frequency, stack count, signal duration and sampling rate.;The source was instrumented with accelerometers on both the moving coil and reaction mass, as well as a strain gauge between the moving coil and coupling device. Preamplifiers for these sensors were designed and built by the author. These signals, along with the output from the sound card, were recorded during many of the field tests so that their use as reference signals for crosscorrelation could be evaluated.;An engineering seismograph was used as the recording device, along with geophone and hydrophone arrays as receivers. A geophone array coupled optimally to the earth was used to record walk-away or normal moveout (NMO) records. A hydrophone array was used to record vertical seismic profile (VSP) records. (Abstract shortened by UMI.)