asperity
unevenness of surface, roughness, and ruggedness
asperity
area on an active fault where there is increased friction, such that the fault may become locked, rather than continuously slipping as in aseismic creep; earthquake rupture generally begins with the failure of an asperity, allowing the fault to move
asperity
individual features of unevenness (roughness) of the surface of a discontinuity, grain, or particle with heights in the range from approximately 0.1 mm to the order of metres