We have used density functional theory to examine the effects of avalanche in adhesion between Fe(100) surfaces, in registry and out of registry. When the central layers of the two surfaces are constrained the surface layers are attracted towards each other, forming a strained crystal region at intermediate interfacial separations. When the constraints in the z-direction are lifted, the surfaces avalanche together. In addition, when the surfaces are allowed to move sideways, we find that an interface initially out of registry will tend to avalanche towards an interface that is in registry.