The Seismic Alert System in Mexico City and the School Prevention Program

Abstract

The Seismic Alert System (SAS) is a public service developed with the sponsorship of the City Government Authorities, with the aim to mitigate seismic disasters. Since August, 1991, after 84 months of continuous operation, the SAS has been able to detect 681 seismic events in the Guerrero Coast; 12 of them so strong as to trigger general alerts in Mexico City, 33 restricted, and one false general alert. The warning ranges strong or restricted correspond to seismic magnitude forecasted great than 6, or great than 5. During the “Copala” M7.3 earthquake, on September 14, 1995 the SAS was activated and issued a general warning signal in Mexico City, 72 seconds prior to the first arrival of “S” ground motion. This earthquake warning reached an estimated population of more than 4 million citizens. The response of children in schools was massive due to the application of an earthquake hazard reduction program. The Copala earthquake helped us to identify strengths and weaknesses of societal response to the earthquake early warning signal. The long-term plan of hazard mitigation of the National Ministry of Public Education, Secretaria de Educacion Publica (SEP), has created an earthquake awareness in the children of various school levels. Even though the children did not suffered the disastrous consequences of the 1985 earthquake, they are today more aware than the average person who lived through that disastrous event and who is still not trained.