Impact analysis is crucial to make decisions among different alternative implementations and to anticipate future maintenance tasks. Several approaches were proposed to identify software artefacts being affected by a change. However, to the best of our knowledge, none of these approaches have been used to study the scope of changes in a program. Yet, this information would help developers assess their change efforts and perform more adequate changes. Thus, we present a metaphor inspired by seismology and propose a mapping between the concepts of seismology and software evolution. We show the applicability and usefulness of our metaphor using Rhino and Xerces-J.