.[1] Surface acceleration caused by the radial modes depends only on the M rr component of the centroid moment tensor and on its depth assuming the isotropic component to be negligible. The 0 S 0 -mode amplitude enables one to obtain a relatively narrow interval of M rr values, whereas 1 S 0 -mode amplitude is more sensitive to centroid depth. We have used these facts to analyze the 2010 Maule (Chile) M w = 8.8 and 2011 Tohoku (Japan) M w = 9.1 earthquakes using PREM. Superconducting gravimeter data available within the framework of the Global Geodynamic Project reveal that the M rr components of these earthquakes should be in the interval 0.95-1.15 Â 10 22 Nm (Maule) and 1.50-1.75 Â 10 22 Nm (Tohoku), respectively. Re-evaluation of the modal quality factors Q is needed to obtain constraints on M rr self-consistently. The joint analysis of gravity data from both events yields Q = 5500 AE 140 for the 0 S 0 mode and Q = 2000 AE 80 for the 1 S 0 mode. We were not able to determine the quality factor of the 2 S 0 mode with an accuracy sufficient to allow meaningful constraints (Q = 1120 AE 270). Citation: Zábranová, E., C. Matyska, L.

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