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Abstract Source parameter scaling for major and great thrust‐faulting events on circum‐Pacific megathrusts is examined using uniformly processed finite‐fault inversions and radiated energy estimates for 114 M w ≥ 7.0 earthquakes. To address the limited resolution of source spatial extent and rupture expansion velocity ( V r ) from teleseismic observations, the events are subdivided into either group 1 (18 events) having independent constraints on V r from prior studies or group 2 (96 events) lacking independent V r constraints. For group 2, finite‐fault inversions with V r = 2.0, 2.5, and 3.0 km/s are performed. The product V r 3 Δ σ E , with stress drop Δ σ E calculated for the slip distribution in the inverted finite‐fault models, is very stable for each event across the suite of models considered. It has little trend with M w , although there is a baseline shift to low values for large tsunami earthquakes. Source centroid time ( T c ) and duration ( T d ), measured from the finite‐fault moment rate functions vary systematically with the cube root of seismic moment ( M 0 ), independent of assumed V r . There is no strong dependence on magnitude or V r for moment‐scaled radiated energy ( E R / M 0 ) or apparent stress ( σ a ). Δ σ E averages ~4 MPa, with direct trade‐off between V r and estimated stress drop but little dependence on M w . Similar behavior is found for radiation efficiency ( η R ). We use V r 3 Δ σ E and T c / M 0 1/3 to explore variation of stress drop, V r and radiation efficiency, along with finite‐source geometrical factors. Radiation efficiency tends to decrease with average slip for these very large events, and fracture energy increases steadily with slip.
Ye et al. (Wed,) studied this question.