Electric Signals on and under the Ground Surface Induced by Seismic Waves
Figure 2
Schematic of the observation system. The pair of reference electrodes measured the vertical component of the earth potential difference (EPD). The positive electrode was buried 2.5 m deep; the negative one was buried 0.5 m deep. The aluminum large plate electrode measured signals related to the vertical component of the atmospheric electricity (AE). The plate area was 4 × 4 m2. It was supported by five insulators at a height of about 4 m. The velocity sensor (only at Sennan), which was fixed on the concrete base of a barn near the sensors, measured the up-down component of the ground surface velocity.
