Heterogeneity of Aftershock Productivity Along the Mainshock Ruptures and Its Advantage in Improving Short‐Term Aftershock Forecast

Abstract This study introduces an improved hypocentral version of the space‐time Epidemic‐Type Aftershock Sequence (ETAS) model, entitled as 3D‐finite source (3D‐FS) ETAS and applies it to analysis Southern California earthquake catalog. By stochastic reconstruction, we are able reconstruct patterns aftershock productivity density along mainshock ruptures. Detailed reveals that: (1) Directly triggered aftershocks make up 21% 41% all earthquakes within rupture areas, show significant spatial heterogeneity temporal migrations; (2) Major tend locate in low at edges clusters formed by small aftershocks; (3) Large slip areas depleted aftershocks, over 60% distributes with less than 0.3 times maximum slip, trajectory pattern on fault plane demonstrates apparent compensation coseismic slip. We relate difference triggering abilities four mainshocks heat flow corresponding regions. Simulation results suggest that 3D‐FS model has advantages improving performance short‐term forecast. Moreover, later more correlated locations subsequent events earlier suggesting migration is important for mitigating hazard.