Forearc Stresses in the Alaska Subduction Zone
In the forearc region of subduction zones, the state of stress depends on the compression induced by the mechanical coupling between the converging tectonic plates and the competing tension induced by the gravitational collapse force on the sloped overriding plate. By quantifying the state of stress in the forearc, the relative strengths of these competing forces can be discerned. The focal mechanisms of earthquakes describe the orientation of the fault and the direction of the slip on the fault that generated the earthquake, and the direction of the slip depends on the state of stress. Therefore, the determination of earthquake focal mechanisms helps to confine the direction of the stresses. Here, by compiling focal mechanism solutions of earthquakes in the forearc region of the overriding plate in the Alaska subduction zone, we determine the spatial variations in the state of stress across the region.