2026/07/01 by Gregory C. McLaskey, David S. Kammer, Chun‐Yu Ke · 1 voice
Earth and Planetary Sciences · #Earthquake Detection and Analysis #High-pressure geophysics and materials #earthquake and tectonic studies
paper · doi:10.1029/2025jb033674
openalex publication_date 2026/07/01 · openalex created_date 2026/07/10 · openalex updated_date 2026/07/22
Abstract Earthquakes occur in populations with few large events and many small ones, yet many earthquake rupture models employ a smooth stress field and other conditions that prohibit the co‐occurrence of large earthquakes and smaller foreshocks and aftershocks. We describe populations of earthquakes that propagate and arrest within a stochastic stress field Δ τ pot ( x ) using a 1D fracture mechanics framework. Δ τ pot ( x ) is characterized by its mean ( mean Δ τ ), standard deviation ( stdev Δ τ ), and scaling exponent ( m Δ τ ), which describes how Δ τ pot ( x ) changes as a function of wavelength. Δ τ pot ( x ) is related to the strain energy that fuels earthquakes, and it embodies the heterogeneous stresses that develop in fault zones with multi‐scale geometrical complexity. Realistic populations of earthquakes, with more small ones than large ones, are produced by highly variable fields with stdev Δ τ (8–80 MPa) that far exceeds mean Δ τ , resulting in significant sections with highly negative Δ τ pot ( x ). Earthquake populations produced by such variable stress fields exhibit b‐values that decrease with increasing mean Δ τ and stress drops that are primarily correlated with stdev Δ τ , are independent of magnitude, and may be limited by the strength of rocks at seismogenic depths. Our preferred models suggest 0 ≤ m Δ τ ≤ 0.25 ( m Δ τ = 1.5 is self‐similar, 1.0 is Brownian, 0 is white noise), consistent with expectations based on multiscale roughness measured on exhumed faults. This suggests that Δ τ pot ( x ) must be highly variable and highly negative, even at short wavelengths, a property that strongly influences the earthquake energy budget but is absent from state‐of‐the‐art dynamic rupture models and unresolvable with kinematic finite‐fault inversions.