I have decided to talk about Paris rather than Chaville, because it belongs to the area close to this city.
Paris and the Ile de France region (region of Paris and area nearby) are not really endangered naturally. There is only 3 things listed as majors risks on the PRIM
website (portal for the prevention of majors risks) :
- transport of dangerous goods
- terrain's movement (settling of the ground for instance)
But this website doesn't list risks related to conflict (like riots, bomb attacks and so on)
France is a very centralised country, and Ile de France is the worst.
Everything in Ile de France goes through Paris : public transports, telecommunications, water, etc.
For instance, when you leave South West of Paris and you want to go to the South of Paris, you need to go from South West to Paris then Paris to South. It generates an extremely important traffic inside of Paris, with giant stations (for instance 450, 000 persons travels each day through the Gare Saint Lazare and 750,000 through Chatelet les Halles)
This centralization makes us extremely vulnerable to terrorism. Though it was smaller bomb attacks compared to others, Paris already had to face that in 1995. The authorities think this might happen again, so the state works a lot on preventing it from happening.
So, here is how a network like Usahidi could be used for in such case :
If a bomb attack actually happened, I think it would be extremely important, at first, to alert all rescuers as fast as possible of where it happened precisely, and how to get there. As you might guess it, a station of 750,000 travellers a day is some kind of labyrinth : even native parisiens get lost here sometimes, so for the rescuers who don't stay long at the same place, it is a real issue.
The second thing is to inform travellers that a problem happened there and that they should find another way. If this is not done, there could be a lot of people stuck at the same place, who can prevent rescuers to go where they are required, and also tragic crowd movement.
The third thing might be to give people the possibility to inform their families and friends that they are safe, to reassure them. On that point, it is important to work on a network strong enough to support thousand of hundreds requests at the same time (in such big event, the phone network is often overloaded)
But when people get hurt or killed in such attack, this should not be learned through a network I think. In France, it is supposed to be announced only in person by a representative of the state, with a psychologist if necessary. I think it is better.