Moment magnitude of Myanmar earthquake on March 28, 2025 from long-period seismic coda

On March 28, 2025, a large earthquake struck central Myanmar and caused massive damage and casualties. The magnitude of the mainshock is a fundamental parameter that both the general public and scientific communities are concerned about. The coda moment magnitude (M_WO) is a new and reliable method for determining the magnitude of large earthquakes, using more than 10 hours of long-period coda waves. We determined the M_WO moment magnitude (with one standard error) to be 7.86 ± 0.03 for the Myanmar earthquake, which is generally larger than the previous reports. The determination includes a small correction (0.02) from our systematic evaluation for smaller earthquakes M_W < 8.3. The M_WO of the Myanmar earthquake is comparable to that of the Kunlun earthquake, and is slightly smaller (0.15 ± 0.03) than that of the 2008 Wenchuan earthquake. The differences are consistent with those from the Global Centroid-Moment-Tensor.