Multiplexed fiber strain sensors for field seismic monitoring

Fibre optic sensors have been widely researched in the field of geophysical science due to their high sensitivity, and can work in harsh environments. In this paper, a strainmeter based on fiber Bragg grating-based Fabry-Perot interferometer is proposed and applied in the field of seismic monitoring. The strainmeters series arrays used the Pound-Drever-Hall technique, enabling accurate strain measurements. A 10-channel array was built, and more than 100 earthquakes and the Earth's daily tidal signals were successfully recorded at the Lijiang National Seismic Station. The FBG-FFPIs had a strain resolution of 4.80 pε/√Hz @ 30 Hz. In addition, a 4-channel array was set up at the Heqing seismic station for comparison. The results showed that the FBG-FFPI strainmeters array has great potential for early warning of earthquakes and can provide abundant seismic data.