Rupture Cascade Initiated by Wastewater Disposal: Nucleation and Domino Effect of Canada's Largest Induced Earthquake

Abstract In 2022–2023, three local‐magnitude (M L ) 4.8–5.6 earthquakes shook the Peace River oilsands area of Alberta, Canada. Previous studies statistically linked the seismicity to nearby disposal activities but lacked in‐depth investigation into triggering mechanisms, including subsurface fluid migration and earthquake interaction. Here, we identify the seismicity as a directional, cascading rupture process initiated by wastewater disposal and sustained by tectonic fault interplay. Our findings highlight the role of regional geologic framework, a combination of a capped fringing‐reef formation and a truncated fault, in channeling injected fluids. Injection above this architecture was effectively isolated, whereas fluids entering the reef formation progressively destabilized the fault, culminating in the M L 5.6 event on 30 November 2022. This mainshock triggered a southeastward rupture cascade, including two M L 4.8+ events on 16 March 2023. Earthquake swarms were primarily nucleated by the nearest reef‐targeted disposal well, with secondary contributions from wells located 20–35 km away.