Analysis of Grace Measurement Data Over Pacific Mega-Earthquake Focus Zones

The paper discusses the features of mega-earthquakes in the subduction zone based on the interpretation of the measurement data of the GRACE space system (SS) regarding these zones. An analysis of digital maps of gravity anomalies in the form of spatial distribution of the EWH parameter was performed relative to the corresponding focal areas of subduction mega-earthquakes that occurred over the past 25 years in the Pacific Ocean. A method has been developed that is used to clarify the sizes of local gravity anomalies that occur in the focal zones of tsunamigenic mega-earthquakes with a magnitude of M> 8.5 using GRACE satellite data. For the experimental part of the research the regions of mega-earthquakes were selected: the subduction zone along Japan where the tsunamigenic mega-earthquake with M=9.1 occurred on March 11, 2011, and the subduction zone along Chile where the tsunamigenic mega-earthquake with M=8.8 occurred on February 27, 2010. It is shown that the GRACE CS measurement data can serve as a basis for estimating the parameters of the mega-tsunami source. The specified data allow increasing the accuracy of solving the corresponding forecasting problems.