北斗三号与超高频GNSS同震形变监测:以2021年青海玛多Mw 7.4地震为例

Objectives: With the completion of BeiDou-3 navigation satellite system (BDS-3) and the development of hardware technology, global navigation satellite system (GNSS) receivers in crustal deformation monitoring network are upgraded towards multi-system and ultra-high rate (≥50 Hz). We aim to study the contribution of BDS-3 and multi-GNSS to coseismic deformation collection and the potential of ultra-high rate GNSS to attenuate the aliasing effect and obtain velocity and acceleration series by using difference methods. Methods: Based on GNSS observation data from the crustal movement observation network of China and continuously operating reference stations in Qinghai Province, we study the 2021 Maduo Mw 7.4 earthquake and obtain coseismic deformation at the nearby stations through kinematic precise point positioning (PPP). Time series before the earthquake are analyzed by time-domain and frequency-domain, namely standard deviation and power spectrum density (PSD). Results: The results show that the accuracy of BDS-3 is about 5 mm horizontally and 18 mm vertically. The accuracy of the multi-GNSS, including GPS, GLONASS, Galileo, BDS-2 and BDS-3, can reach 4 mm horizontally and 12 mm vertically. The results of PSD show that multi-GNSS can contribute to attenuate noise at most frequency and BDS have the lowest noise among all the four systems. Velocity series perform the best at a range of 5-10 Hz, while no acceleration is available at any rate. Conclusions: The accuracy of displacement obtained by BDS including BDS-3 is better than that of GPS in this earthquake. The observation of 50 Hz cannot significantly weaken the aliasing effect which reaches saturation at about 10 Hz. The ultra-high rate velocity and acceleration series obtained by difference method are too noisy for usage. The maximum sampling rate of GNSS seismic monitoring can be set at 5-10 Hz which represents a good trade-off between effect and cost.