Analysis For Seismic Recording Capacity Of GPS Network In Fujian Province

This study is based on the years of cumulative data from GPS stations and seismic stations at the same location in Fujian Province and the data recorded by strong motion instrument and GPS of air-gun excited experiment in a reservoir,using the frequency domain integral method which convert the velocity record and acceleration record into displacement record.The analysis of spectrum,correlation and difference of displacement time history are also carried out.The main works of this paper are as follows:1.The strong worldwide earthquakes that occurred in recent years are selected,and according to the data obtained by the seismic instrument,the ability of GPS to record the seismic event is synthetically judged.The difference analysis of 8.6 magnitudes earthquake event in Sumatra show that the lithology of observational station has great influence on the consistency of the observed results.Additionally,the different of the instrument pier will cause certain effect to the coincident degree of the amplitude and phase.Therefore,in the process of construction of the two nets fusion,the influence of lithology on consistency and the amplification effect of GPS's observational pier on displacement amplitude should be paid attention to.The root mean square(RMS)of noise in 5 minutes GPS's record before 8.1 magnitudes earthquake in Nepal is calculated.After removing the long period trend,the average precision of the north and east is 3.26mm and 3.57mm respectively.When the RMS amplitude of displacement exceeds the level of noise,the GPS's record is clear.The analysis results of the 8.0 magnitudes earthquake in Japan show that GPS does not have a good record in some far field earthquake events which seismic surface wave is not developed enough.2.Under the action of air-gun source,the floating platform violent shaking.The air-gun source not only can make floating platform produce rotational displacement which the maximum of up to 1 meters or more,but also contains many kinds of frequency information.So,the air-gun source experiment can be used to study the recording ability of GPS under complex displacement condition.This paper analyzes several different types of air-gun source experiment.According to air-gun source experiment's results of the 2015 Mianhuatan reservoir and the 2016 Nanyi reservoir,under the action of complex displacement,the position's difference has an influence on the consistency of the displacement record of the GPS and strong motion instrument.The comparative analysis of the floating platform's steady state experiment and the free state of floating platform experiment show that in the observational environment with strong rotational motion,the difference between the two displacement records becomes more obvious,the reference coordinate system of the strong motion instrument is changed with the rotation of the floating platform.However,the GPS's reference coordinate system does not change under the complex observational environment;this is the main reason for the difference of the displacement record between the GPS and the strong motion instrument in the same position.Moreover,the rotation angle information recorded by GPS can effectively correct the displacement record of strong motion instrument in the complex observational environment with rotational motion.