Finally, the target area is the region where the alarm messages must be spread so that people can leave the area or take a certain action to contain the emergency effects. Clearly, due to human mobility and message broadcasting, the alarm messages can also spread outside the target area and, based on the case, this effect can be suitable or not. However, since the target area is defined as the area where the emergency actually affects people, in this work we are mainly interested in characterizing the alarm diffusion in such an area.