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The Guerrero Accelerograph Network was installed in 1985 with the goal to obtain near-field records on rock sites from an anticipated M~ 8 earthquake in the Guerrero gap, which was identified at the time as the most probably gap to rupture along the Mexican subduction zone. An early success was obtaining nearfield records from the September 19, 1985 Michoacan earthquake (M= 8.1). With National Science Foundation and Mexican support, the network has operated continuously to the present. The result is a set of over 3600 accelerograms from over 1800 earthquakes through the end of 2004. These include 105 events with M> 5. With a magnitude range from under 3 to 8.1, the data are excellent to study scaling ground motions on rock. These will also provide a uniform record to study changes, if any, in seismic source parameters over time in this region where a great earthquake is still expected.

The Guerrero network began with 12 bit digital instruments recoding on digital cassettes. With time, old equipment was replaced with new technology (solid state memory, 19+ bit a/d), and with the GPS system for timing, so better records have been obtained even from small earthquakes. To accommodate varied and changing instrument types, institutions in Mexico in charge of seismic arrays have developed a Mexican Strong Motion Database. Guerrero records are disseminated on the web and CD-Rom products from the Mexican Strong Motion Database.