Constraints on the centroid moment tensors of the 2010 Maule and 2011 Tohoku earthquakes from radial modes
Abstrakt
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 S-0(0)-mode amplitude enables one to obtain a relatively narrow interval of M-rr values, whereas S-1(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 x 10(22) Nm (Maule) and 1.50-1.75 x 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 +/- 140 for the S-0(0) mode and Q = 2000 +/- 80 for the S-1(0) mode.
We were not able to determine the quality factor of the S-2(0) mode with an accuracy sufficient to allow meaningful constraints (Q = 1120 +/- 270). Citation: Zabranova, E., C.
Matyska, L. Hanyk, and V.
Palinkas (2012), Constraints on the centroid moment tensors of the 2010 Maule and 2011 Tohoku earthquakes from radial modes, Geophys. Res.
Lett., 39, L18302, doi: 10.1029/2012GL052850.