Investigation on signal characteristics of high-rate GPS and accelerometer by airgun active source experiment

High-rate GPS plays an important role in seismological research, however, the stability and applicability of its seismic signals are still unclear; benefiting from the relatively high repeatability of airgun seismic sources, it can provide quantitative source waveform signals for analysis, which is especially suitable for analyzing and calibrating the signal characteristics of instruments. We compared and analyzed the signal characteristics of high-rate GPS and accelerometer at different frequency bands based on the information of high-rate GPS and accelerometer obtained from the active airgun source experiment in May 2016 at Nan Yi Reservoir, Zhangzhou, Fujian. It is found that: (1) the sinking depth of the airgun, the size of the gun array and the water depth affect the correlation coefficient between the two types of signals ; (2) the displacement record of high-rate GPS is in good consistence with the corrected displacement signal recorded by accelerometer, and the correlation coefficient is highest in the 10-60 s frequency band; and the displacement of highrate GPS record is more stable than that of accelerometer at longer periods. The comparison shows that high-rate GPS can be used as a "displacement meter" for seismic observation and has unique advantages in the near-field observation of large earthquakes, which can be an effective supplement to seismograph observation. In addition, high-rate GPS can be applied to earthquake early warning, intensity fast reporting, as well as rapid determination of the rupture process of strong earthquakes.