Separating P and S waves through a multielectrode piezoelectric sensor with a symmetric structure

ABSTRACT In seismic signal analysis, separating the P- and S-wave components is a crucial yet challenging task. Different from methods that rely on signal postprocessing, a sensor is developed to directly output the P- and S-wave components of seismic waves by using the inherent symmetry of stress waves. For a hollow piezoelectric circle, P waves generate equivalent electrical potentials in two semicircles, whereas S waves induce opposite potentials in adjacent quadrants. Thus, a sensor designed using a hollow piezoelectric cylinder with four electrodes enables P- and S-wave separation through simple algebraic operations on the output signals. The validity of this concept is first confirmed through finite-element simulation. Then, compression and shear fatigue tests are conducted to test its realistic performance. The numerical and test results indicate that P- and S-wave signal outputs do not interfere with each other and that the sensor accurately reflects the ratio of P to S waves in the case of a composite body wave. In summary, the developed sensor allows simplification of signal processing for separating the P- and S-wave components of a composite wave through sensor structural design by using the intrinsic symmetry of body waves.