Seismic phenomena in tke light high-rate GPS precise point positioning results

Abstract

The motion of GPS permanent stations during three earthquakes has been investigated with the use of Precise Point Positioning (PPP) technique and the data obtained by seismic sensors. The study examines the ability of high-rate GPS observations to reflect the ground motion retrieved by the strong motion instruments (SM), considered to be more reliable and precise. The goal of this article is to show the sensitivity of GPS PPP kinematic high-rate positioning with position domain filtering using the band-pass Butterworth filter on small samples of position time series. The kinematic PPP approach in RTKLib software was used, supported by the CODE precise orbit and clock products to estimate positions from 5-hour long GPS phase datasets. Obtained position time series were reduced to 5-minute samples covering the time of co-seismic motion. The application of Butterworth band-pass filtering of GPS and SM time series increased the agreement between them up to 72% in terms of correlation, resulting in correlations within the range 0.34 to 0.99. The comparison of peak ground displacements (PGD) revealed that for Italian events, GPS-SM absolute value of the average difference is 6 mm with GPS-SM distances within the range of 0.05 to 2.14 km. In all analysed earthquakes, the agreement between GPSgrams and seismograms in terms of the first P-arrival polarity was checked and it was found that it is consistent in all cases. This confirms the GNSS technique capability for determining fault plane solution for earthquakes with magnitudes over 6.

Detection of Structural Vibration with High-Rate Precise Point Positioning: Case Study Results Based on 100 Hz Multi-GNSS Observables and Shake-Table Simulation

“…The high efficiency for seismic waveforms in GNSS estimates of this filter has been recently proven, for example, in the work of [37]. The selected threshold in the frequency domain allows the elimination of all the above indicated factors excluding short-term variations of coordinates related to the clocks residuals (mostly caused by less stable internal oscillator of receiver).…”

Galileo High Accuracy Service in Real-Time PNT, Geoscience and Monitoring Applications

“…The accuracy of displacements obtained with CNS corrections is 12 mm horizontally and 25 mm vertically, while the accuracy of time series acquired with HAS corrections is slightly inferior, measuring 20 mm horizontally and 46 mm vertically. Nonetheless, denoising is necessary for the HR GNSS time series to reliably assess earthquake-induced vibrations due to low-frequency noise [33]. To this end, both time series are subjected to high-pass filtering with a cutoff frequency of 0.01 Hz.…”

Using GNSS Phase Observation Residuals and Wavelet Analysis to Detect Earthquakes

“…Currently, the PPP technique is the most commonly used technique for earthquake studies (Kudlacik et al 2019;Tu et al 2013) due to the limitations of the double-difference method (Li et al 2018), where the position changes of the reference station may occur and preclude the use of double-difference method. PPP can accurately and efficiently determine the magnitude (Fang et al 2013;Geng et al 2016) and epicenters of earthquakes (Fang et al 2013).…”