Situating a abstract problem in a nearby setting is a regularly used communication technique. Also in this ad from the Portuguese AMI, Assistência Médica internacional.
The location is Terreiro do Paço (official name: Praça do Comércio), a square in Lisbon where many ministries of the Portuguese government are located. This place is often seen as the center of political power in the country, although the parliament and the presidential palace are somewhere else. Imagine a better place for a disaster. If it happens there, everybody would help. Every country, city and their citizins should be prepared.
Copy: Um dia a AMI pode ter que o ajudar. Ajude agora a AMI.
One day AMI may have to help here. Help AMI now.
Vitor who is helping me lot with translating and explaning about Portuguese campaigns told me: in fact many people died on that place in 1755, people ran towards the river because of the earthquake, but get caught by the tsunami that followed. You can read more about it in this Wikipedia article.