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Open access to GNSS permanent network data in case of disasters

Natural or man-made disasters on Earth are the cause of large-scale material and social damage. One of such catastrophes is earthquakes that hit the territory of the Republic of Croatia several times during 2020. The devastating earthquakes in Zagreb (March 22, 2020) and Petrinja (December 29, 2020) prompted a study to strengthen the ability to respond to such situations and provide fast and reliable information on disasters in the field of geodesy and geoinformatics. Preparedness, management, response, but also an understanding of events such as an earthquake, is unthinkable today without GNSS data and permanent GNSS networks. One of the main obstacles to using this data is their openness and availability. The application of permanent GNSS networks is widespread in many areas, and today the data collected by GNSS stations are increasingly used to support seismotectonic in monitoring Earth crust deformations caused by earthquakes. Various studies have shown that GNSS stations recorded terrain compressions before the earthquake, which can indicate the possibility of an earthquake occurring. Also, satellite methods can determine the horizontal and vertical displacements of stations before, during, and after the tremor at greater distances from the epicenter. This indicates that there is great potential for the application of GNSS permanent network data in earthquake impact assessments on natural and man- made structures on Earth (Šugar and Bačić 2021). The problem of using GNSS permanent network data arises in their availability. In order to be accessible, the data must be open, access should be simplified, free, and user-friendly. Some networks, such as IGS or EUREF EPN, apply a policy of open access to GNSS station observation data through their Internet portals where they distribute data from national networks of GNSS stations included in the global and/or European permanent network. For most needs, such as positioning and navigation, these data have satisfactory quality. The problem arises when more precise and reliable data of high registration rate is needed. Access to such data is possible within the national GNNS permanent networks, but it is limited and requires the registration of users, and payment of fees for the data use. High registration rate data as well as a dense network of GNSS stations are becoming more and more important for the study of seismological activities (Šugar and Bačić 2021). Encouraged by the fact that earthquakes are one of the most devastating natural phenomena and the need to improve preparedness for such situations and mitigate the consequences, research was launched in the form of a global survey of institutions responsible for GNSS networks to gain insight into their open access data policies in case of disasters (Latinčić, 2021). The focus of the research is on defining the global picture of GNSS permanent network data availability with an emphasis on the openness of high-frequency network data needed to research seismological activities that have an impact on both economic and social aspects of human lives. The results of the survey show whether countries use special models of data access in case of disasters and the readiness of countries for international cooperation, standardization, and data exchange of GNSS networks at the global level in case of large- scale disasters.

Earthquakes, Global survey, GNSS networks, Open access

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