Estimation of Frequencies and Splitting of ₂S₁ and ₃S₁ Modes from the IGETS Superconducting Gravimeter Network Data after the 2013 Sea of Okhotsk Earthquake

Abstract

For the first time, the 2S1 and 3S1 modes of the Earth’s free oscillations following the largest deep-focus earthquake in the Sea of Okhotsk on May 24, 2013, have been analyzed using the maximum likelihood method. Data from 14 superconducting gravimeters of the IGETS network deployed in the central part of Europe were used for the analysis. Estimates of the time of mode excitation after the earthquake origin time, degenerate frequencies, and mode splitting parameters are obtained.