The $50 earthquake alarm that could save thousands of lives

In September 1985 a devastating earthquake measuring 8.1 on the Richter Scale smashed into Mexico City killing 10,000 people and leaving parts of the city in ruins.

Since then, the populous Latin American nation of 122 million has invested in one of the most advanced seismic warning systems anywhere in the world. The SASMEX facility came online in 1991 and reacts to data gathered by sensors placed near major fault lines along Mexico's Pacific coast.

Receivers dotted around five major cities, including Mexico City and Acapulco, will sound the alarm if they detect an earthquake. It's a system that can buy vital seconds for residents to brace themselves before the tremors begin.

But not everyone has access to a SASMEX receiver -- there are 100,000 in operation but at a cost of roughly $330 apiece, they are a luxury the majority of Mexicans can't afford.