Mexico City, Mexico - The Mexico City Center for Emergency Response and Civil Protection service released a free app this week for Blackberry mobile users that would alert residents to an impending major earthquake.

Mexico City has been rocked by tremors strong enough to cause tall buildings to sway a few times already this year. BlackBerry users with the application will receive a warning up to 50 seconds in advance, depending on where the epicenter is located, before the quake reaches Mexico City. “Even a few seconds warning will be valuable in helping people take action to protect their lives,” said Mayor Marcelo Ebrard.

Until now, the only advance-alert system available here had been the one developed by Mexico's National Autonomous University and was provided to a limited number of subscribers, including several government agencies.

When a 7.4 magnitude earthquake shook southern Mexico on March 20th, video footage of the early earthquake warning system shows a successful evacuation of the Mexican Senate.

Mexico City, with its sprawling and often haphazard construction, is especially vulnerable to severe damage from an earthquake because parts of it sit on soft soil or landfill that acts like jelly during a seismic event.

The geography of the Mexican capital city allows seismological centers on the coast to detect tremors seconds before the quake hits inland, making Mexico among only a handful of countries to implement an early earthquake warning system.

In last month's temblor, as in many that Mexico City gets, the epicenter was in the southern state of Guerrero, allowing time for the alert to be raised, but if a quake is coming from Michoaca it won’t ring as the alarm is only connected to seismic stations in the area of Guerrero.

For now, the app is only available for Blackberry users, although it will eventually be developed for Android and Iphones. City officials say the app is available free of charge on this website: caepccm.df.gob.mx.

The system will emit a sound and a vibration, even when the BlackBerry is in silent or standby mode for moderate and strong quakes (5.0 or greater.) The system can only be tested when the seismic alarm is activated (a real event.)

Ebrard also said his government's goal in the coming weeks is to install up to 6,800 alarms in public streets that will convey the warning to a broader public. "We want to have the most complete seismic-alert system in the world," Ebrard said.