Determination of Radiated Energy and Energy-Moment Ratio for the 2025 Xizang Dingri 6.8Magnitude Earthquake

Radiated seismic energy is a quantitative characteristic of an earthquake that depends not only on the initial and final stresses, but also on the rupture history, and reflects the dynamic characteristics of the source. The seismic wave energy radiated per unit of seismic moment, or energy-moment ratio, represents the balance between the stress drop, source rupture velocity, and variation in the shear wave velocity. Earthquakes with a high energy-moment ratio thus release strain energy more rapidly. The accurate and rapid determination of radiated seismic energy and the energy-moment ratio play an important role in seismic hazard assessment, quantitative earthquake research, and engineering seismology research. In this study, waveform data from the Global Seismographic Network were used to measure the dynamic source parameters of an earthquake that occurred on January 7, 2025, in Dingri, Xizang, with the radiated energy, energy-moment ratio, slowness parameter, and apparent stress investigated. Static source parameters such as the seismic moment and moment magnitude were also determined. The main results were as follows: (1) the radiated energy of the earthquake was 9.73×10¹⁴ J, corresponding to an energy magnitude M_E of 7.1, with a source rupture time of 24 s; (2) the focal mechanism was normal faulting, with the seismic moment of 4.98×10¹⁹ N·m corresponding to a moment magnitude M_W of 7.1. Nodal plane I was focused at 191°/32°/−67° while plane II was at 344°/60°/−104°, and the centroid depth was 12.3 km; (3) the energy-moment ratio of the earthquake was 1.95×10^–5, the slowness parameter was −4.71, and the apparent stress was 0.59 MPa. The energy-moment ratio was thus higher than the average for normal fault earthquakes on the Chinese Mainland. In conclusion, the results indicated that the 2025 earthquake was a normal fault earthquake with relatively high energy release efficiency and significant potential for damage to local buildings and the infrastructure, as verified by the severe damage to ground structures and significant casualties nearby.