Traditionally, the high frequency components of earthquake loading are disregarded as a source of structural damage because of their small energy content. I argue that the higher frequency waves travelling through stiff masonry structures can trigger two types of failure mechanisms that have not yet been taken into account. First, the high frequencies can cause small vertical inter-stone vibrations that result in irreversible relative displacements of the stones causing collapse. The energy needed to cause this deformation and failure comes from potential gravitational forces. The second failure mechanism is associated with the outward thrust from the partial liquefaction of the loose inner core of the wall.