The applicability of aerospace technology varies with the kind of hazard. Some are limited in extent and require high resolution images while for others low resolution satellite data are appropriate. The magnitude of a disaster caused by high-intensity low-frequency natural events depends on the susceptibility (S) of the land and the vulnerability (V) of the society. Risk R = fS.fV.
Aerospace data give the spatial extent of disasters and thus serve in emergency operations. Data acquisition then is time-critical; high temporal resolution and all weather capability are essential. More important is the use for disaster preparedness. The imagery needed then is not time critical and other capabilities (spatial/spectral resolution, 3D info, etc.) determine the selection of sensors. The survey should result in hazard zoning to guide physical planning and in monitoring to issue early warnings.