Relationships of Seismic Source Parameters and Magnitude for Mw ≥ 7.0 Earthquakes

Abstract

Abstract

Literature-based compilation indicates that there have been 165 earthquakes with moment magnitude Mw ≥ 7.0 in the period 1980–2024 for which identifiable source-parameter estimates are available. Despite the relative scarcity of such events globally, this dataset is sufficiently large to perform a robust rupture analysis. Using ordinary least-squares regression, we characterized the relationships between Mw and eight source parameters: rupture length (L), rupture width (W), rupture area (S), maximum slip (Dmax), average slip (D- -), average rupture velocity (Vr), source-averaged static stress drop (Δσ), and rupture duration (TR). The logarithms of rupture length, width, area, maximum slip, and average slip generally showed statistically significant linear relationships with Mw. In contrast, average rupture velocity and static stress drop showed weak and mostly statistically insignificant relationships with Mw. Rupture duration was more strongly correlated with Mw for reverse/thrust- and normal-fault earthquakes than for strike-slip earthquakes. Strike-slip earthquakes had a mean length-to-width ratio of 3.97, compared with 2.05 and 2.43 for reverse/thrust- and normal-fault earthquakes, respectively. For the 25 events with both maximum- and average-slip estimates, the ratio Dmax/D- - ranged mainly from 1.5 to 3.5, with a mean of 3.18, indicating spatially heterogeneous slip distributions. Because the dataset was compiled from studies using different source models and inversion methods, the resulting equations should be interpreted as dataset-specific empirical relationships.