Physical modelling

Henry C. Bland, Joe Wong, Eric V. Gallant, Kevin W. Hall

CREWES has been developing and improving its ultrasonic physical modelling facility. This modelling facility is capable of simulating seismic surveys in 3 dimensions over scaled down earth models composed of plastics and metals. Unlike prior physical modelling systems at the U of C, this one uses high precision linear motors with a 0.1 um optical measuring system to execute and measure the survey with great precision. In 2005, components for a new modelling system were purchased, and the new system was designed and major components were test-assembled. Progress has been made on three fronts: First, much of the necessary fabrication and assembly has been completed. Several hundred electrical connections have been wired, and a new circuit board was designed and assembled to indicate the status of the eight drive motors. Second, a series of programs have been written to intelligently operate the modelling system's drive motors based on a high-level seismic survey design. Simulation has proved useful in verifying correct operation of the software. Third, a change of source signal generation strategies has been proposed. By changing from an impulse source to a swept-frequency source we hope to improve the signal to noise ratio of physical modelling data. A numeric analysis of the swept-frequency source illustrates the benefit of this change.