Figure 9
Response of the LaCoste & Romberg D#185 gravimeters for different vertical excitation frequencies and amplitudes. The blue rhombuses are obtained by moving the vibration platform in the vertical direction with a frequency signal between 1 and 18 Hz and amplitude equal to 1 mg. The red squares and black triangles indicate amplitude movements of 0.5 and 0.18 mg, respectively (a). A linear relationship is found between the gravity readings and the excitation amplitudes at 2 and 3 Hz (b).