Detection limit to Earthquakes and seamounts of Quantum gravimeter payload combined with satellite-satellite tracking from single GRACE type to multiple couples constellations

Advancements in space-based gravity observation are poised to undergo a significant transformation in the coming years, propelled by innovations such as the MAGIC constellation, featuring a single polar pair GRACE-C, and the enhanced ESA’s NGGM inclined pair, boasting lower orbit altitudes and drag compensation capabilities. This trajectory is further bolstered by the potential integration of augmented satellite constellations equipped with absolute accelerometers utilizing Cold Atom Interferometer technologies. These developments promise lower spectral noise curves, thereby enabling higher time resolution and a superior spatial resolution compared to current standards set by GRACE-FO. Our exploration extends to pioneering applications within the domain of solid earth sciences, encompassing seismic events, seamount formations, vertical topographic shifts, and fluid reservoir dynamics, all of which stand to benefit from the forthcoming advancements in gravity observation from space. While phenomena linked to the earthquake cycle and postseismic fault movements are effectively monitored on land through SAR and GPS, their observation in remote oceanic regions remains challenging due to the absence of seismic waves generated by slow fault movements. We delineate the observable magnitude limits contingent upon fault mechanisms, depths, and satellite constellations. Similarly, the detection of seamounts, particularly in remote areas where they may silently grow, altering underwater bathymetry in uncharted ways, presents a formidable task that could potentially be addressed through future spaceborne gravity observations (Braitenberg and Pastorutti, 2024). The vertical topographic movement is documented by GPS and SAR, leading to a mass change which we compare to competing mass changes as the hydrologic and glacial mass loss in the Alps and to the detectability levels of the future satellite constellations. We finally show that in future the isolated gravity signals for the tectonic movements are complementary to data used in the Copernicus Services of a) Disaster Management and b) Climate Change Monitoring and are prone to improve the completeness of these Services.