From the Baylor College of Medicine, this page (aimed at teachers of Biology) offers an in-depth look at what it takes to create the imagery from which emergency planners do after-action analysis, resource allocation and focus recovery work.
“To determine where the need is the greatest, planners require accurate information about the extent and location of the damage.
Airplanes and helicopters can capture detailed images. However, to be useful, these images must be pieced together and matched to scale, and even sunlight angle. In such cases, satellite images are preferable, because capture wide regions at one time.”
Particularly moving are the high-resolution slides (with explanatory notes) of the coast of Sendai before and after the tsunami.