Tidal Interplate Lithospheric Deformation of Earth
Last Updated: 28/05/2024 11:19 Created at: 02/05/2024 07:37
Final Presentation of NAVISP Project EL1-047 now available:
On Thursday April 25th, 2024, DIAN – DIAN S.r.l., together with SAPIENZA – Sapienza University of Rome and the RIGCT – Research Institute of Geodesy, Topography and Cartography, presented the results of the NAVISP EL1-047 project " TILDE- Innovative concept for the Risk Assessment of Geologic Hazards using GNSS and Solid Earth Tides Modelling”.
Recent analysis has identified a statistical relationship between tidal forces originating from the Moon and Sun and the incidence of earthquakes. However, existing GNSS (Global Navigation Satellite System) geodetic models do not adequately account for local factors that significantly impact how the Earth's crust responds to tidal stress, thereby impeding accurate hazard forecasting. Incorporating these local tidal effects into GNSS modelling has the potential to improve hazard prediction by associating them with geological events.
To address this gap, this project aimed to investigate the deviations in site-displacement vectors compared to predictions from the International Earth Rotation and Reference Systems Service (IERS) model. Specifically, the main objectives of the TILDE Project were to utilize the PPP (Precise Point Positioning) absolute approach to estimate GNSS coordinates, explore the possibility of defining a local behaviour of Solid Earth Tides (SET) dependent on position on Earth, and investigate potential correlations between Local Solid Earth Tides (LSET) and tectonic activity, seismicity, and volcanic hazards. This involved assessing the applicability of the current global IERS-2010 SET model in geodesy and understanding how local variations in SET may relate to geological phenomena such as earthquakes and volcanic eruptions. Using high-quality GNSS data, the project generated and analysed time-series data of site-displacement vectors across a wide range of global sites. In some instances, gravimeter data was also incorporated to enhance the analysis.
For the investigation of tectonics within the TILDE Project, GNSS data was employed from a global network with a sampling rate of 1 day. During this analysis, the Local Permanent Tide (LPT) was switched off while the Solid Permanent Tide (SPT) was activated to minimize noise levels and ensure consistent data for tectonic movement studies. Furthermore, for the examination of earthquakes, GNSS data was utilized from the global network with a sampling rate of 3 hours, with all tide models deactivated, specifically focusing on the SPT components K1 and M2. This configuration enabled precise monitoring of ground movements associated with seismic activity. Lastly, in the study of volcanoes, GNSS data from a regional network with a sampling rate of 3 hours was employed over a time span exceeding a couple of years. During this period, tide models were switched off, and attention was directed towards the SPT components K1 and M2, facilitating the detection of ground deformation patterns indicative of volcanic activity and enabling the study of volcanic hazards over time.
The research revealed persistent local deviations over extended periods of geological stability and identified short-term correlations between local deviations and seismic or volcanic events, including periods of increased activity leading up to events and subsequent periods of decreased activity. In conclusion, this project represents a significant advancement in understanding the complexities of site displacement, with implications for various disciplines such as geodesy and seismology.
Future enhancements could involve leveraging AI and machine learning, especially unsupervised methods, to integrate local data on crust and mantle rigidity. Additionally, analysing the latest GNSS solutions obtained in Kinematic mode with a high sampling rate could enhance the assessment of daily and sub-daily tidal constituents. Establishing a dense global GNSS network has the potential to provide valuable earthquake precursors, including Total Electron Content (TEC), Zenith Total Delay (ZTD), Strain Rate, and Love Number evolution, thus improving prediction capabilities.
The project was carried out in the scope of NAVISP Element 1, which is dedicated to technology innovation of the European industry in the wide PNT sector.
More detailed information can be found in the slides of the Final Presentation.