Estimation of Ground Stiffness, Ground Viscosity and Captured Ground Mass Using Vibrator Field Measurements

Near-surface velocity measurements are very valuable for making static corrections in data processing to improve the quality of subsurface images in land seismic surveys. Ali et al (2003) show that the near-surface velocity can be estimated by using ground elastic properties produced from modern vibrator control systems. Direct measurements via uphole surveys can be cost prohibitive. The modern seismic vibrator driven by the feedback control system produces a force to the ground as it vibrates. As the vibrator pushes against the ground, it gets a counter force from the ground. The motion of the ground responding to the applied force is detected through the movements of the baseplate. The dynamic of the vibrator normally is described by the accelerations of the reaction mass and the baseplate, which can be used to estimate underlying ground properties. Accurate estimates for ground properties can only be achieved when key elements are in place including a valid reaction mass-baseplate-ground model and a properly implemented good estimation algorithm. This paper describes a useful method for estimation of ground properties using the reaction mass and baseplate accelerations as a vibrator shakes.