In-Situ Calibration Of Borehole Strainmeter Observation Based On Record Of Rayleigh Waves By Colocated Seismometer

In order to capture gentle tectonic strain for volcano dynamics,seisomogenesis dynamics,etc.,high-sensitivity borehole strainmeters had been installed at the relevant observatory for scientific research,which has advanced the development of volcano dynamics,geodynamics,and earthquake prediction.The calibration of borehole strainmeter is fundamental to borehole strain observatory.The calibration of borehole strainmeter based on the calculated reference strain signals from theoretical Tide model gives systematic error because of the uncertainty of theoretical Tide model.Because of non-uniform strain reference signal caused by inhomogeneity at measured scales,in-situ calibration for borehole strainmeters based on measured strain reference signal has low precision.In order to increase calibration precision for borehole strainmeters based on measured strain reference signals,this thesis is devoted to the investigation of in-situ calibration method for borehole strainmeters based on the reliable reference uniform strain signal from collocated borehole seismometer at PBO network.Firstly,the dynamic caibration model for incident Rayleigh strain wave and instrumental response in semi-infinite space by the combination of wave-function expansion and the superposition of the P and S components of the incident Rayleigh strain wave.Secondly,in-situ calibration method of borehole strainmeters based on collocated borehole seismometers has been presented to discuss the applicability of the recommended dynamic caibration model for incident Rayleigh strain wave and instrumental response in semi-infinite space,which will benefit not only borehole strain observation but also high-frequency strain seismology,volcano dynamics,and geodynamics.