The ₀S₀ fundamental mode excited by Sumatra-Andaman earthquake: Parameters assessment using the maximum likelihood method

This paper presents new estimations for all parameters (amplitude, frequency, quality factor, and initial phase) of the ₀S₀ Earth fundamental mode, which was triggered by the 2004 Sumatra-Andaman earthquake with a magnitude of M_W9.1. Sixteen records from the IGETS superconducting gravimeters have been analyzed. Using the maximum likelihood method algorithm, frequency, initial phase, and amplitude estimates have been acquired with remarkable accuracy. The values of frequency (814.6568 ± 0.0002 μHz) and quality factor (5455 ± 17) obtained in this study differ slightly from those of the PREM model, and the amplitude variations qualitatively correspond to those of the SKS12WM13 model. The estimated time delay between the onset of the earthquake and the excitation of the mode (290 s) is consistent with the moment tensor analysis from the USGS National Earthquake Information Center.