Surface slip distributions and geometric complexity of intraplate reverse-faulting earthquakes

Abstract Earthquake ground surface ruptures provide insights into faulting mechanics and inform seismic hazard analyses. We analyze for 11 historical (1968–2018) moment magnitude (Mw) 4.7–6.6 reverse earthquakes in Australia using statistical techniques compare their characteristics with magnetic, gravity, stress trajectory data sets. Of the total combined (summative) length of all (∼148 km), 133 km (90%) to 145 (98%) align geophysical structure host basement rocks. Surface rupture (SRL), maximum displacement (MD), probability at a specified Mw are high compared equivalent globally. This is attributed (1) steep cratonic crustal strength gradient shallow depths, promoting hypocenters (∼1–6 km) limiting downdip widths (∼1–8.5 (2) favorably aligned anisotropies (e.g., bedrock foliations, faults, fault intersections) that enhanced lateral propagation and/or displacements. Combined (modeled observed) MDs middle third SRL 68% either ≤33rd or ≥66th percentiles 16% probability. MD occurs proximate directly within zones geometric complexity (as evidenced from ruptures) 8 (73%). approximated by 3.3 ± 1.6 (1σ) × AD (average displacement). S-transform analyses indicates high-frequency slip maxima also coincide complexities, consistent amplifications variability due kinematic interactions neighboring faults. Rupture taper angles exhibit large variations (−90% +380% respect mean value) toward termini steepest where terminate obliquely oriented magnetic lineaments lithology changes. Incremental approximates between 10th 90th SRL. The average static drop studied 4.8 2.8 MPa. A classification scheme stable regions presented describe prevailing intraplate across diverse structural-geophysical settings. New scaling relationships suggestions logic tree weights provided enhance probabilistic bedrock-dominated continental regions.