The Next Generation Gravity Mission (NGGM): A breakthrough in our understanding of Solid Earth dynamics.

Space gravity missions play a key role in our understanding of planet dynamics. SLR allowed us to constrain the rheology of the mantle and the ice loss in Antarctica and Greenland at low harmonics and GRACE, at harmonic l=60 for the time dependent gravity field, confirmed and improved these SLR discoveries. For the static field GOCE constrains the dynamics of subduction and rifting, disclosing in-depth density anomalies and the coupling between the plates, for the knowledge of the genesis of large earthquakes. In this regard, GRACE demonstrated the feasibility of gravity data to obtain the fault characteristics of large earthquakes, Mw=8.5 - 9 by adding, compared to the classical seismology, the benefit of uniform data coverage. Based on these results and on just accomplished findings from new studies, a breakthrough is expected from NGGM, an ESA/NASA double-pair gravity mission at l=250 spatial resolution for the time dependent gravity field, to detect the slow gravity changes due to active tectonics and the co-, post- and inter-seismic phases of earthquakes as low as Mw=7 - 7.5.