Monitoring of geophysical deformations on a regional scale using the low-cost GNSS collaborative network CentipedeRTK

Developed since 2019, the CentipedeRTK network is a permanent collaborative GNSS network whose main objective is to make RTK positioning freely available, mainly using low-cost receivers and antennas. Since its creation, the network has grown considerably, well beyond the borders of France, and now includes more than 800 base stations. The main sector using the network is agriculture, but more and more public and private organisations and individuals are also using it.  

The geoscience community quickly became interested in the network, first as users of RTK positioning (for sea level monitoring, drone surveys, etc.) and then for post-processing of the raw measurements from the base stations. Since mid-2022, the RENAG network data centre has therefore been archiving the data from the base stations on a daily basis with the aim of using them for geoscience applications. A first study based on data acquired in 2023 has demonstrated the value of these data for monitoring atmospheric water vapour over continental France. 

Here we focus on the use of data acquired by CentipedeRTK base stations located in mainland France to monitor geophysical movements on a regional scale. To this end, the daily positions of the CentipedeRTK stations estimated in PPP using GipsyX are analysed and compared with those estimated for nearby permanent stations belonging to conventional networks. There is a slight deterioration in the repeatability of the mean positions (15 to 20% depending on the component). The time series show an increase in dispersion, but a very good consistency of the variations is still observed. The discrepancies observed can be explained by the equipment of the CentipedeRTK stations, in particular their antenna, as well as by the direct environment of the stations, which is not always as optimal as that of conventional stations.  

These results will be used to develop a set of recommendations for CentipedeRTK contributors and will help to increase the value of the data collected by the network's base stations for geoscience applications.