El Arrayán Fault (Spanish; Castilian: Falla El Arrayán) is a geological fault, located inmediataly north of the city of Santiago in Chile. The fault runs in northwest-southeast direction. Likely, the fault was last active sometime in the Quaternary period (last 2.5 million years).[1] It is chiefly a strike-slip fault. Fault scarps, sag ponds, mountain saddles and stream deflection are some of the surface features of El Arrayán Fault.[1] The fault is estimated to be able to produce 6.4 Mw-strong earthquakes which make it a significant risk factor for the northernmost neighbourhoods of Santiago.[1]