Sessions

1. Tides and non-tidal loading in space geodetic and subsurface observations

Conveners: Jean-Paul Boy (ITES-EOST, Strasbourg, France), Umberto Riccardi (Università di Napoli Federico II, Naples, Italy), Hartmut Wziontek (BKG, Leipzig, Germany)

The session addresses the entire range of tidal and non-tidal phenomena, both at the theoretical and at the observational level. Tidal phenomena influence terrestrial as well as satellite-borne acquisitions over a wide frequency band, ranging from seismic normal modes to the Chandler Wobble and beyond. The response to tidal forces and to the dynamics of geophysical fluids depends on the Earth’s rheology and allows to constrain its properties. On the other hand, it is essential to take these effects into account in the processing of astronomical, satellite gravity mission, space geodetic and terrestrial gravity observations in order to isolate other signals, like transients due to global change or water storage variations.

We invite any contribution related to the modelling and the analysis of solid Earth and Ocean tides as well as studies on surface loading due to oceanic and atmospheric tides, non-tidal geophysical fluid circulation (atmosphere, ocean and continental hydrology). Tidal studies of planets are also welcome.

2. Geodesy for hazard monitoring (seismo- and volcano-geodesy, etc.).

Conveners: Daniele Carbone (INGV - Osservatorio Etneo, Italy), Xiaodong Chen (Chinese Academy of Sciences, Wuhan, China), Filippo Greco (INGV - Osservatorio Etneo, Italy)

Geodetic techniques are extensively utilized to monitor natural and man-made hazards. Precise measurement and joint analysis of ground deformation and gravity changes are key to assess hazards at active volcanoes, as they provide a window on bulk volume and mass changes associated with magma transport. Integration of seismic data with geodetic information permits to capture the full dynamic range of ground motions generated by large earthquakes and can provide information on the long-term deformation patterns of seismically active fault systems, thus improving the characterization of their seismic hazard. Furthermore, geodetic measurements are making fundamental contributions to mitigating the impact of other geohazards, such as debris flows, landslides, land subsidence and sea level changes.

This session aims to provide a comprehensive overview and contributions focused on the application of geodesy to different geohazards are welcome.

Invited speaker: Cheinway Hwang (Department of Civil Engineering of Yang Ming Chiao Tung University, Taïwan)

3. Monitoring of subsurface fluids (hydro-geodesy, hydro-gravimetry, geothermal monitoring, etc.).

Conveners: Carla Braitenberg (University of Trieste, Italy), Marta Calvo (IGN Madrid, Spain)

The session invites studies which link subsurface fluids and geodetic observations. The session should display the broad range of natural and anthropogenic fluid movements which can be detected through geodetic observations. The hydrologic signal can be interpreted as noise or signal, according to the viewpoint and aims of the observer. The hydro-geodetic phenomenon could be interesting in itself, or because the process in which fluids are involved is the main goal.

We welcome all techniques used to subsurface monitoring and surveillance for different purposes over decades. Both the instrumentation used by these techniques as well as the precision obtained have been improving over time, obtaining great results that can be combined with each other to provide a better idea of the local behavior of the Earth's subsurface.

Currently, major challenges in subsurface hydrologic monitoring include the need to monitor large areas, as well as streamline some observation and data analysis processes to improve time consumption and precision obtained. We welcome theoretical studies, as well as case histories, as observations in labs, or from industrial plants, as for instance those of geothermal energy production or where fluids are injected and extracted from the Earth. In dry regions the main concern is to detect subsurface water, which is a welcome subject where linked to geodetic observations.

Invited speaker:  Maite Benavent (Complutense University of Madrid, Spain) 

4. New technologies, software and innovative concepts (cold-atom gravimetry, gradiometry, etc.)

Conveners: Przemyslaw Dykowski (Institute of Geodesy and Cartography, Warsaw, Poland), Sébastien Merlet (LNE-SYRTE, Observatoire de Paris, France), Markus Krutzik (Humboldt-Universität, Berlin, Germany)   

Modern instrumental developments for which tidal phenomena and geodynamics are relevant are gravimeters and gradiometers based on superconductivity, atom interferometry, micro-electromechanical-system (MEMS) gravimeters, Inertial Measurement Units, gravitational wave antennas, satellite gravimetry and atomic clocks. The improvements in gravimetric instrumentation lead to the use of gravimetry as a tool to detect underground mass changes, as naturally occurring hydrologic draughts or fluids injected into the underground for the purpose of temporary storage for instance. In the next couple of years, instrumental developments in portable absolute gravimeters are expected, and further innovations can be envisaged from the atomic interferometry technology.

The proposed session allows all new, unusual and open-minded concepts related to both measurement and analysis of any type of phenomena related to monitoring Earth dynamics. As processing capabilities of modern computers no longer limit the complexity of the possible analysis schemes, new, complex methods of data analysis are no longer a limitation.

Contributions are encouraged especially related to measurements with new types of evolving sensors such as portable cold atom gravimeters, gradiometers, MEMS gravimeters on all spatio-temporal scales ranging from point wise measurements, tidal records to regional scale measurements on moving platforms as well as satellite atom-interferometry concepts. At the same time, new or updated software concepts as well as data analysis methods are welcomed.

Invited speaker: Camille Janvier (Exail, France)

5. Time variable gravity and mass redistribution (glacial isostatic adjustment, ice mass changes, ocean dynamics, etc.)

Conveners:     Maaria Nordman (Aalto University/NLS, Finland), Holger Steffen (Lantmäteriet, Sweden), Roman Sulzbach (GFZ Potsdam, Germany)

The Earth's gravity field and its dynamic variations are pivotal for monitoring mass transport and distribution within our planet's system. Gravimeters serve as essential tools, offering diverse applications spanning tectonics, hydrology, oceanography, and cryospheric studies. They enable the observation of critical processes such as land uplift, glacial isostatic adjustment, ice melting, and alterations in ocean currents.

This session delves into the observation, analysis, and interpretation of high-resolution temporal gravity changes. It encompasses various gravimeter types, including space-borne, superconducting, absolute, relative, and marine variants. Topics of interest involve analyzing Earth tides, understanding the impact of water storage fluctuations across different scales, and exploring geophysical applications such as geothermal fields, volcano monitoring, and the study of loading effects.

Contributions are encouraged on innovative utilization of space missions like GOCE, GRACE, GRACE-FO, and other low Earth orbiters, often in conjunction with GNSS techniques, InSAR, radar altimetry, and in-situ observations. Additionally, approaches addressing the challenge of isolating signals of different geophysical origins, leveraging model output, advanced processing, and estimation techniques, are highly welcomed.

Invited speaker: Rebecca McGirr (Research School of Earth Sciences of the Australian National University (ANU), Canberra, Australia

6. Temporal variations of the Earth’s rotation

Conveners: Christian Bizouard (SYRTE, Observatoire de Paris, France), Xiaoming Cui (Chinese Academy of Sciences, Wuhan, China)

The temporal variations of the Earth's rotation reflect the dynamics of the entire Earth system, in which the& time scales range from seconds to decennia, the spatial scales from local, continental to global dimensions and the depth scales from the surface to the core. In that session we welcome talks that highlight the significant progresses achieved over the last years in observing and explaining these temporal variations. We seek contributions for the following topics:

The last day of the Symposium (Friday, August 30, 2024), will be dedicated to IAG business meetings.