This research involves the analysis of broadband and short-period earthquake source characteristics of moderate to great earthquakes, and examining variations of source properties with depth, size, focal mechanism, and tectonic regime (e.g. slab thermal parameter). First, current work will be continued on stacking broadband and short-period P waves of deep earthquakes recorded by the National Net and by short-period regional arrays to obtain time functions. Second, this approach will be extended to the subset of moderate to large shallow earthquakes with moment and depth such that rupture terminates before the arrival of obscuring depth phases, that is, reflections from the Earth's surface above the earthquake. The goal is to compare time histories of earthquakes from 30 to 650 km depth and enable the systematic characterization of shallow rupture termination, a process hidden in the depth phases of the most commonly studied large, shallow earthquakes. This set of time functions will also characterize the transition from shallow to deep faulting, suggested by the drop in aftershock productivity as depth increases, as well as help constrain the mechanism of deep seismic faulting. ***
