Soil amplification response of Mexico City clay in the MS7.1 Puebla, 2017 earthquake

Soil response of soft alluvial deposits along Mexico City valley is examined during the 19 September 2017, M(S)7.1 Puebla earthquake. The seismic event occurred approximately 120km south-east of the capital Mexico City, and the recorded peak ground accelerations were lower than 0.2 g on the top of deep soft deposits. However, substantial damage was inflicted on residential infrastructure with numerous collapses and many victims in Mexico City. Recordings were available in more than 50 stations in Mexico City, including motions on rock and on soft clay profiles. The response spectra amplification ratio is calculated and presented for the most characteristic soil profiles, not only for the M(S)7.1 Puebla event but also for previous earthquakes with magnitude larger than 7. Site effects are studied in terms of simple one dimensional wave propagation of simplified profiles. The effect of three different G-gamma and xi-gamma curves (Vucetic & Dobry, Darenteli, and elastic) on the overall soil response is investigated. Comparison of the calculated with recorded accelerations is presented as well as their response spectra.