Design and simulation of a vertical broadband seismometer

In this paper, a new vertical broadband seismometer is designed, simulated, and evaluated. The proposed seismometer has a bandwidth from 40 s to 50 Hz and sensitivity to ground velocity of 1500 V’/m/s. The mechanical suspension used in the proposed design is a mass-leaf spring rotational pendulum. The displacement of the seismic mass is sensed by a laser interferometer and then forwarded to an electronic force feedback system which feeds a linear actuator to keep the mass almost fixed in its position. The current needed to fix the mass in its position is an indication of the ground acceleration. The performance of the simulated seismometer is evaluated by applying a data record of two actual earthquakes to the simulated model and comparing its response to the earthquakes with that of a real seismometer (Trillium-40) having the same bandwidth and sensitivity. The proposed seismometer has performed within 0.4 % residual variance for the local event and 0.03 % residual variance for the regional one compared to Trillium-40.