Centrifuge physical modeling technique has been increasingly used in geotechnical earthquake engineering. A centrifuge dynamic model test has been conducted on the centrifuge on a saturated sand deposit model. The input motion at the base of the model was a strong earthquake waveform with a peak acceleration of 0.55 g in prototype. Some interesting phenomena, which include disappearance and reappearance of acceleration in soils during the shaking event, and existence of double plateaus or one plateau and one peak in the time histories of excess pore pressure, were recorded. The mechanism behind the phenomena was investigated by comparing the time history of excess pore pressure with the time history of acceleration, and with the derived shear modulus.