Performance of GRACE Mascon Solutions in Studying Seismic Deformations

Abstract

AbstractGRACE (Gravity Recovery and Climate Experiment) mascon (mass concentration) solutions are widely used in cryosphere science and hydrology research. Mascon solutions have been demonstrated to perform analogous to or better than spherical harmonic (SH) solutions at the basin scale. Although the mascon solutions are expected to facilitate an improved local recovery of seismic gravity signals of large earthquakes, the application of mascon solutions to earthquake analysis remains to be investigated. In this study, we examine the performance of the mascon solutions for seismic gravity signals induced by three M9 class (2011 Tohoku‐Oki, 2004 Sumatra, and 2010 Chile) and three smaller earthquakes and compare them with SH solutions and theoretical gravity changes modeled according to the dislocation theory. We analyze the coseismic and postseismic gravity changes and conclude that the mascon solutions contain information almost identical to the SH solutions and retrieve coseismic gravity change signals with resolutions equivalent to Gaussian filter radii of 210–270 km. The mascon solutions have strengthened gravity change signals of approximately twice the strength of the SH solutions. However, mascon solution cannot fully recover the complete seismic deformation since it is still a spatially “band‐limited” data set that uses the spatial smoothing in the aggressive regularization. We found that the mascon solutions contain “seismic‐like” gravity change signals several months before the Tohoku‐Oki and Chile earthquakes occurred.