Extracting longitudinal waves by utilizing the symmetry of piezoelectric sphere

Abstract

Dividing the P- and S- wave components from measured body wave signals is a pivotal yet formidable task for various seismic monitoring devices. In contrast to the commonly employed post processing methods, here, we report a sensor designed to directly extract P-wave signals by filtering out the S-wave component from body waves. The design principle of the sensor capitalizes on the inherent symmetry of a spherical piezoelectric shell and body waves, resulting in the superposition of P-wave excitation charges while concurrently canceling out S-wave excitation charges. The validity of this concept was first confirmed through theoretical analysis and numerical simulations. Laboratory tests further substantiated that the sensor response to P-waves surpasses that to S-waves by two orders of magnitude. The reported sensor sheds sights on the processing of body waves with hardware and validates a new pathway for improving the performance of existing related devices.