MEXICO CITY, Apr 04 (AP/UNB) — Mexico City's government is offering a free app for BlackBerrys that will alert users when a major earthquake is approaching the capital.

Mayor Marcelo Ebrard says there are monitoring stations in remote areas of the country that detect earthquakes and send signals to Mexico City from 5 to 10 seconds before a tremor's waves reach the capital.

Ebrard says the app began working Tuesday. He says even a few seconds warning will be valuable in helping people take action to protect their lives.

At some point, the city plans to use the monitoring system to set off sirens that would alert all residents.

Two weeks ago, a 7.4-magnitude temblor damaged hundreds of homes in southern Mexico and caused panic far off in the national capital.