Method and system to determine the azimuthal orientation of borehole seismometer sensor using long period surface waves in microseisms

Abstract

The present invention is a method to determine an azimuthal orientation of a borehole seismometer sensor performed by a computing device using a control server having a database and an arithmetic function, the computing device performing a method to determine the azimuthal orientation of a borehole seismometer sensor using long-period surface waves in microseisms, including step Sin which a data collection unitcollects continuous waveform data recorded by a borehole seismometer and a reference seismometer; step Sin which a frequency band setting unitsets a frequency band to be analyzed in the collected continuous waveform data; step Sin which a filtering unitperforms bandpass filtering on the frequency band to be analyzed; step Sin which a waveform dividing unitdivides seismic waveform into waveform segments with preset time units; step Sin which a phase shift unitshifts the phase of the divided vertical component waveforms by 90°; step Sin which a waveform calculation unitcombines the divided N' and E′ component seismic waveforms to calculate horizontal components for rotation angles waveform between 0 and 360° from the N′ orientation; step Sin which a correlation calculation unitcalculates a correlation coefficient between the horizontal and vertical component waveforms; step Sin which a Rayleigh wave orientation determination unitrepeats steps Sto Sfor each divided time domain; step Sin which an orientation comparison unitperforms steps Sto S, respectively, with respect to the borehole seismometer data for which the sensor orientation is to be determined and the reference seismometer data for which the sensor orientation is already known; and step Sin which a result calculation unitaverages θ determined for each time period to calculate a final result.