f Seismic Vibrator Impedance And Near-Surface Properties

Since the early days of Vibroseis, it has been observed that the vibrator behavior differs for<br>different near-surface conditions. In its simplest form, the earth can be regarded as a spring,<br>resulting in a baseplate motion that decreases with increasing earth stiffness (increasing spring<br>constant). It was also observed that this simple spring model was accurate for low frequencies<br>but inadequate to explain the baseplate motion for higher frequencies, where several<br>resonance phenomena were observed in the vibrator response.