Detailed investigation of seismic hazardous areas and scientific field investigation of earthquakes share common features that, firstly, both practices have the characteristics of systems engineering because multidisciplinary knowledge and techniques are needed; secondly, both activities are hard to plan (in the traditional sense) because the earthquakes have limited predictability (at least at the present time); and thirdly, both the investigations have been playing critical roles in deepening the understandings of the mechanism and predictability of earthquakes. The only difference is that the detailed investigation of seismic hazardous areas is conducted prior to an earthquake, and the scientific field investigation is conducted shortly after the earthquake. In this chapter we discuss these two practices in parallel or in a comparative view. The discussion is in the form of a project to facilitate practical operations. To meet the challenges in the planning, one of the important concepts is scenario earthquake ruptures which is the basis in the design of the monitoring/observational systems.