Earth Science And Geology Practice Exam

Moment magnitude measures the total energy released by an earthquake, expressed through seismic moment. Seismic moment combines how stiff the rocks are, how large the fault area that slipped is, and how much slip occurred. In formula terms, the seismic moment is proportional to the area of fault rupture times the average slip (and the rock’s rigidity), and Mw is a logarithmic scale derived from that moment to give a uniform sense of an earthquake’s size across events. This focuses on the overall energy radiated by the quake, not the intensity at a single site or the duration of shaking. Peak ground acceleration reflects instantaneous shaking at a location, and the duration depends on rupture propagation and path effects, not the total size. The area of fault rupture is part of what contributes to the moment, but Mw is about energy release, making it the best answer.