Component azimuths of the permanent seismic stations in the Northeast China estimated from P-wave particle motion

Modern seismic studies rely on reliable three-component seismological observations, whether the station sensor’s north component strictly aligns to the geographical north or not will directly affect the accuracy of the research. However, due to magnetic anomalies near the station or artificial error, the azimuth of seismometer may be deviated. In this study, the component azimuths of 154 permanent seismic stations in Northeast China were rechecked using the P-wave particle motions based on the teleseismic events in 2020, and we used the same seismic events to calculate the component azimuth by the principal component analysis and the signal-to-noise-weighted-multievent method, respectively. The azimuth deviation determined by these two methods are very consistent, with a correlation coefficient of 0.998 6. Among the 154 stations, the azimuth of 84% of the stations deviate slightly from the true north, and some of the stations have some sort of problems, including azimuth deviation of the two horizontal components （＞20° or ＜−20°） or polarity reversal in one or more components. We found a large deviation in sensor azimuth could result in incorrect estimatiog of both crustal thickness and v_P/v_S ratio by H-κ stacking. Therefore, in order to ensure the reliability of seismological analysis, the azimuth of the station needs to be checked and calibrated regularly.