Inversion Method on Azimuth Angle Orientation of Non-direction Borehole Strain Meter

Abstract

Borehole strain technique has been widely used in geophysics and earthquake departments. Earthquake Administration of Beijing Municipality fixed several borehole strain meters, and got high-quality data, but they didn’t measure the apparatus’ azimuth angle because of being limited by techniques, resulting in a failure in orienting for the borehole strain meter, impeding the exploitation of tide information. Therefore, determination of the azimuth of borehole strain meter is very significant; Therefore, based on that solid tide’s theoretic value could be calculated, considering observation data and its main influencing factors, and using developed Nakai solid tide fitting model, we proceeded effective simulation with the borehole strain observational data of Gubeikou station and the nonlinear particle swarm optimization method, we obtained the apparatus’s azimuth angle of the station, then we did an actual test of the inversion model with the other time observation data and the obtained optimizing solution and got satisfactory results. The inversion and analysis process of Borehole strain azimuth angle orientation indicate that the azimuth angle inversion scheme is feasible and the model has high accuracy, the result is significant for fully using borehole tide observation data to study geodynamic and earthquake forecast.