Mexican Seismic Alert System

The Mexican Seismic Alert System (Spanish: Sistema de Alerta Sísmica Mexicano or SASMEX) is the earthquake warning system covering portions of central and southern Mexico. It currently provides up to 60 seconds' warning of earthquakes to Mexico City, Acapulco, Chilpancingo, Morelia, Puebla City, Oaxaca City and Toluca. SASMEX is administered by a non-profit civil association, Center for Seismic Instrumentation and Registry (Spanish: Centro de Instrumentación y Registro Sísmico, A. C. or CIRES).

The SASMEX sensor network serving Mexico City has been regarded as the first earthquake early warning system issuing alerts available to the public. SASMEX supplies regular information of all kinds, including reports of earthquakes of all magnitudes, and drills, via Twitter, under the name AlertaSísmica SASMEX. All earthquakes are reported as #TenemosSismo (we have an earthquake); warnings of serious ones are delivered as #AlertaSismica (earthquake alert).

The 1985 Mexico City earthquake prompted a national rethink of earthquake and emergency preparedness measures. The government of Mexico City sponsored the placement of accelerometers throughout the city in 1987, allowing data to be obtained on ground movements in the area. With the support of the local government, CIRES developed Mexico City's earthquake alert system, which began operating with 12 sensors in 1991 and has been publicly available since 1993.

CIRES was tapped to develop a similar system for the state of Oaxaca after it was struck by a M_w 7.4 earthquake in 1999. Beginning in 2000, CIRES and the state government developed an early warning system for Oaxaca, which entered into service in 2003. The two formerly separate earthquake warning systems were combined in 2005 to form SASMEX.

The SASMEX system contains 97 sensors, primarily along the coast from Puerto Vallarta south, in the mountains of the state of Guerrero, and in northern Puebla and across most of Oaxaca. An expansion to the network of 28 sensors, currently in development, would add monitoring capabilities in Oaxaca's Isthmus region, inland portions of Veracruz, and the western two-thirds of Chiapas.

...
Wikipedia