As an Incident Commander I would call vertical evacuation a strategy if my objective was determined to be “provide for the immediate safety of coastal residents after a strong offshore earthquake”. There are several strategies I could evaluate to meet my objective other than vertical evacuation. Once I determine that vertical evacuation is my chosen strategy, I now need to identify the resources necessary to accomplish the mission, and perhaps even specific tasks. If I were a hotel owner operating a beach-side resort, I may call vertical evacuation my chosen tactic for keeping my guests safe and train my staff in how to accomplish the tasks necessary, as well as orient my guests upon check-in.

As for pros and cons, I would always say that evacuating out of harms way before harm gets there is great if you have the luxury of warning time and the capacity to move people. On the other hand, one coastal community I did emergency planning for is at risk for a large earthquake (strong enough to damage bridges), followed by a series of tsunamis. In this case, safety is a mile inland or above the predicted waterline. The only way to get inland is to cross two bridges which may or may not survive the earthquake. In this case, vertical evacuation to large standing structures may be the best viable option to survive the first tsunami arriving in about 20 minutes.

I believe the use of vertical evacuation is best suited for escaping the immediate danger of water inundation (tsunami or flood), but it could prove useful in short term use as a protective action due to a chemical hazard release with a heavier than air product. Of course if we are talking an indoor environment, the HVAC and elevator system would have to be controlled immediately as well to eliminate them as vectors for movement of the hazard.

We used the concept of vertical evacuation for protecting herds of animals due to their pastures being in an active flood plain. Large earthen berms were created to allow for high ground for the animals as flood waters would rise. This type of mitigation strategy would work for animals as well as people if building codes were such that a certain percentage of an area were required to be above the known inundation zones. I believe you will see this strategy employed in rebuilding along the coast of Japan to ensure that large populations of people are relegated to higher ground and only those industries and people necessary along the water level will be allowed.