Mexico City Sinking Fast

by Diego Cevallos

The city, which was literally a lake until the year 500, will suffer serious water supply problems in ten years' time. The city's water pipes will become dislocated and roads and buildings could start to crack if the present pattern of water extraction and consumption goes unchanged.

Furthermore, the city -- one of the world's biggest -- will become more vulnerable to seismic movement and earthquakes, phenomena which could appear with great destructive force at any moment in the next 50 or 100 years.

Each inhabitant of the Mexican capital consumes 320 liters per day, an amount higher than that of other large cities like Sao Paolo or Tokyo, which have levels of below 250 liters, according to official data.

This excessive consumption is compounded by increasing amounts of waste and insufficient waste water treatment capacity, meaning supply sources have already been contaminated.

These warnings were given by representatives of the non- governmental Ecology and Development Center of the Independent National University of Mexico (UNAM), who are pressing for rapid change in the Mexico City water supply system.

Ivan Restrepo, spokesman for the Ecology and Development Center, said the city must reduce its demand and limit use of underground sources as the ground is already cracking.

The natural wet and clayey condition of the subsoil could magnify seismic waves and provoke greater destruction in the event of earth tremors, warned Cinna Lomitz, a UNAM seismologist.

The Mexican Pacific coast is a point of contact for subterranean tectonic plates, which register periodic movements. At some point in the next few years an earthquake strong enough to reach Mexico City is expected.

Seismic tremors, with their epicenter in the Pacific ocean, killed hundreds of people and destroyed dozens of buildings in the capital in 1985.

With the ground becoming less firm and sinking, possibilities of damage in the case of earthquake or heavy rains increase, said the UNAM expert.

The capital was put on red alert in September when heavy rains caused flooding. Eleven people died and 600 homes were affected.

Extraction of water from underground has caused the city to sink some 11 meters in the last 100 years, according to a study by the Mexican Ecologist Movement.

Mexico City is on ground unsuitable for construction, admit municipal authorities.

Mexico valley "is not the place to build a city," and "that was clearly stated by the first engineer who came here from Spain" in the 16th century, said Lommitz.

The Aztec city of Tenochtitlan, which formed the basis of modern Mexico City, was surrounded by water when the Spaniards arrived. The conquistadors decided to reclaim the area, by embarking upon immense engineering works.

The indigenous city planners had managed to establish their city in the middle of the lake, avoiding floods by using hydraulic systems, but the Spaniards modified the surroundings, a decision which has left a legacy of problems down to the present day.

For experts say the city is sinking, and plans to bring in water from other zones are slow, expensive and coming far too late.