Phys.org September 1, 2022
Researchers in France conducted a global analysis of Gravity Recovery and Climate Experiment (GRACE) reconstructed gravity gradients from July 2004 to February 2011 to test whether the deep signals preceding the March 2011 Tohoku earthquake could be detected before the event as a specific feature originating from solid Earth. They improved the angular resolution of the gravity gradients using two overlapping ranges of azimuthal sensitivity to investigate short-term signals of large amplitude aligned with the orientation of the Northwestern Pacific subduction and set-up a method to identify consistent solid Earth signals shared by different GRACE gravity models. They showed that the dipolar gravity gradient anomaly before the Tohoku earthquake was nearly unique in space and time in the GRACE GRGS03 solutions. The preseismic gravity gradient increase was highly consistent between the GRGS03 and CSR06 solutions, independently from their respective oceanic corrections, and could be clearly distinguished from rare anomalies of similar amplitudes all associated with the water cycle over continental areas. According to the researchers their work offers solutions for the continuous monitoring of the Pacific subduction belt to document transient slabs motions in real time from global satellite gravity fields, and their relationship with shallower deformations and seismic events…read more. TECHNICAL ARTICLE
…Continuous gravity monitoring of the Pacific subduction belt might highlight where big earthquakes may occur. Credit: U.S. Navy/Mass Communication Specialist…