The Feasible Study of Detecting High-Degree Coseismic Gravitational Changes

Aiming to detect the high-degree coseismic deformation of the gravitational anomaly. Gravity Recovery and Climate Experiment (GRACE) is designed as satellite-to-satellite tracking (SST) to recover the time-varying gravity field, and Gravity Field and Steady State Ocean Circulation Explorer (GOCE) carries a set of satellite gravity gradiometry (SGG) to obtain the gravity gradient change. As the GOCE mission directly measures the gravity gradient change which is a high-frequency physics, it contains unique short-wavelength information that GRACE lacks. The SST and SGG are combined to recover the coseismic gravitational deformation up to degree 200, although the SGG was originally designed to recover static fields with high precision. The least squares spectral combination method is used in our study to combine two kinds of data in a spherical harmonic domain. The approach of detecting the high-degree coseismic gravitational deformation is proposed though the current SGG data are not accurate enough to extract coseismic information. Coseismic gravitational deformation in four independent seismic sources is calculated to discuss the minimum requirement of the observation based on the spherical earthquake dislocation. Furthermore, with the remarkable improvement of the accuracy of GRACE-FO, the next-generation gravity mission will probably provide sufficient precision to allow us to obtain high-degree gravitational deformation of the coseismic.