In case of earthquake

Mexico City was built on the dried lake of Texcoco - some of the city's foundations are not over solid ground, but on a spongy wet mass which amplify the effects of seismic activity elsewhere.

Some are wondering if the city is due for a big shock - the last big earthquake was 25 years ago and left 10-thousand people dead.

A worrying sign is the banners installed recently by Civil Defense around the city, telling people to be prepared.