Moment Magnitudes of Two Large Turkish Earthquakes in February 2023 from Long-Period Coda

Abstract

Two large earthquakes occurred in south-central Turkey on February 6, 2023, causing massive damages and casualties. The magnitudes and the relative sizes of the two mainshocks are essential information for scientific research and public awareness. There are obvious discrepancies among the results that have been reported so far, which may be revised and updated later. Here we applied a novel and reliable coda moment magnitude method to the two large earthquakes. The magnitudes (with one standard error) are 7.95±0.013 and 7.86±0.012, respectively, which are larger than all the previous reports. The first mainshock is slightly larger than the second one by 0.11 in magnitude and the difference is statistically robust (exceeding three standard errors).

Keywords: 2023 Turkish earthquakes, coda waves, moment magnitude, long-period