Coseismic Gravity Changes and Crustal Deformation Induced by the 2018 Fiji Deep-Focus Earthquake Observed by GRACE and GRACE-FO Satellites

Earthquakes at depths of ≥300 km are generally called deep-focus earthquakes. Only two earthquakes with Mw 8.0 or more have occurred in this century—the 2013 Okhotsk earthquake (Mw 8.3) and the 2018 Fiji 8.2) on 19 August 2018. However, was only reported seismographs, related crustal deformations were not observed by Global Navigation Satellite System because observation network did exist around epicenter. This study analyzed time series gravity data Gravity Recovery And Climate Experiment (GRACE) its successor, GRACE Follow-On, detected spatial distribution coseismic changes mainly due to deformation earthquake. The results consistent numerical calculation when using fault parameters estimated seismic waves. Thus, calculations used construct a uniform slip rectangle model explain provide map deformation. is based changes; thus, new research combining satellite gravimetry wave will be necessary future.