A new DAS sensor prototype for multicomponent seismic data

Abstract

We present a novel type of multicomponent sensor prototype that uses distributed acoustic sensing (DAS) technology. A prototype of the new sensor has three individual parts consisting of optical fiber wound around a polyvinyl chloride frame. We deployed the sensor prototype at a test site and recorded seismic waves generated by a wooden hammer. A geophone array was also set for comparison purposes. The data observed with the new DAS sensor prototype show good agreement with the conventional geophone. The particle motion of waveforms obtained by the DAS sensor prototype shows ellipsoidal motion, the propagating velocity of which coincides with the velocity of the Rayleigh waves estimated by the dispersion curve based on the geophone data. We introduced a simple string model to explain the dynamic behavior of the sensor. The analysis results of the string model can explain features of recorded seismic data. These results indicate that the DAS sensor prototype records seismic waves via lateral vibration of the string. The present study shows a new possibility of the multicomponent sensor with the DAS technology.