On the feasibility of detecting coseismic gravity-change signals of the 2023 Turkey double earthquakes from satellite gravimetry

This study focuses on the feasibility of detecting coseismic gravity changes from inland large earthquakes using Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) observations. The 2023 Turkey double earthquakes (M_W7.8 and M_W7.5) serve as the specific case study. Dislocation model predictions indicate that the peak-to-peak coseismic gravity changes range from -0.10 to +0.06 μGal at the spatial resolution of GRACE-FO monthly gravity field solutions. An RMS analysis of CSR RL06 data (2018-2025) demonstrates that observation noise reaches up to 1.26 μGal over the near-field region of the Turkey double earthquakes. This indicates that the noise amplitude exceeds the target signal by an order of magnitude, which suggests that the coseismic gravity-change signal is difficult to detect. Moreover, uncertainty estimation using the discrepancies between the GLDAS and WGHM land surface models shows that the hydrological model uncertainty reaches up to about 2.59 μGal, which further hinders the feasibility of coseismic signal detection. Furthermore, simulative tests indicate that improved precision in both GRACE-FO observations and hydrological models is necessary to detect the coseismic signals of earthquakes comparable to the Turkey double earthquakes (about M_W7.8). For marine earthquakes, GRACE-FO noise needs to be reduced to 60% of its current level. For inland earthquakes, besides the reduction of GRACE-FO noise, the hydrological model errors should be reduced to 5%. Consequently, successful GRACE/GRACE-FO detection of the effect of inland earthquakes with a magnitude of around M_W8.0 or lower requires advancements in satellite gravimetry coupled with enhanced hydrological models.