Low frequency seismic characterization of underground sites with tunable mechanical monolithic sensors

This paper describes the application on a new mechanical implementation of an inertial seismic sensor, configurable also as an force-balanced accelerometer, consisting of monolithic full symmetric Folded Pendulum equipped with an high sensitivity optical readout. The seismic sensor is, therefore, compact, light, scalable, resonant frequency tunable, with large measurement band, low thermal noise and with good immunity to environmental noises. The measured minimum displacement noise is in very good agreement with the theoretical ones. Typical applications are in the field of earthquake engineering, geophysics, civil engineering and in all applications requiring large band-low frequency performances coupled with high sensitivities.