| 22 Jun 2026
Global controls on aftershock productivity: roles of magnitude and tectonic setting
Abstract. Aftershock productivity varies substantially among large earthquakes, yet the relative roles of magnitude, tectonic environment, and source properties remain incompletely resolved at the global scale. Here we perform a comprehensive, data-driven analysis of aftershock productivity for all Mw ≥ 7.0 mainshocks worldwide since 1976, using a homogeneous workflow based on USGS/NEIC catalogs, PB2002 plate-boundary geometries, and uniformly defined aftershock windows (r ≤ 200 km, t ≤ 30 days, M ≥ 4.5). Mainshock events are classified into three tectonic domains—subduction, other plate boundaries, and intraplate/crustal—allowing systematic comparison of productivity patterns across geodynamic settings. Across all tectonic classes, aftershock productivity scales linearly with mainshock magnitude in log-space, with nearly identical slopes (b ≈ 0.76–0.81), indicating a universal magnitude-controlled triggering mechanism. In contrast, intercepts differ significantly among tectonic environments: subduction earthquakes are systematically the most productive, followed by other plate-boundary events and intraplate earthquakes. Depth and distance to the nearest plate boundary exert weaker but physically interpretable secondary influences, with productivity decreasing for deeper ruptures and for intraplate events located far from plate boundaries. Residual analysis and multivariate correlations confirm that magnitude and tectonic setting explain the dominant share of global variability, whereas depth and distance provide secondary, context-dependent modulation. Together, these results establish the first unified, physically interpretable global framework of aftershock productivity, quantifying both universal magnitude-driven scaling and environment-specific productivity offsets. The findings provide actionable constraints for global ETAS parameterization, operational aftershock forecasting, and seismic-hazard models for future great earthquakes.
1. The manuscript uses the M scale throughout the analysis . Recent studies have questioned the use of the M scale for earthquakes below M 7.5, arguing that the extension of the Hanks and Kanamori (1979) formulation to smaller magnitudes is based on Equation (1) of Purcaru and Berckhemer (1978) which was originally developed for earthquakes up to Ms 7.0 (Das et al., 2025; Das and Das, 2026). Furthermore, Matsu'ura (2025) discussed theoretical limitations of the M scale. These studies are not considered in the manuscript. Since earthquake magnitude is the primary variable controlling the statistical analyses presented in this study, the authors should justify their use of the M scale and discuss whether alternative magnitude formulations, such as the Mwg (Das magnitude) scale, would influence the reported relationships and conclusions.
2. A revised magnitude scale (Mwg or Das magnitude scale) has recently been proposed to address the reported limitations of the M scale using a global earthquake dataset (Das et al., 2025). The proposed scale has been shown to exhibit a closer relationship with radiated seismic energy and existing magnitude scales. Although Gasperini and Lolli (2025) criticized the Mwg scale, more recent studies have challenged several of their main conclusions (Paul et al, 2025; Das et al, 2025; Das and Das 2026). Since earthquake magnitude is the fundamental parameter in this study, the authors are encouraged to compare the results obtained using both the Mw and Mwg scales and discuss whether the choice of magnitude scale affects the regression models, statistical relationships, and overall conclusions.
References
1) https://www.nature.com/articles/s41598-025-06642-1
2) https://link.springer.com/article/10.1186/s40623-025-02278-7
3) https://link.springer.com/article/10.1007/s40098-024-01147-6
4) https://link.springer.com/article/10.1007/s12046-025-02769-z
5) https://www.sciencedirect.com/science/article/pii/0040195178901774